CONTRIBUTIONS FROM THE RfUSEUM OF PALEONTOLOGY
THE UNIVERSITY OF MICHIGAN
VOL. XIX, NO. 11, pp. 143-155 (2 pls., 2 figs.)
TWO NEW CRINOIDS OF THE
FAMILY PERIECHOCRINITIDAE FROM THE
MIDDLE DEVONIAN THUNDER BAY LIMESTONE
ROBERT V. KESLING
MUSEUM OF PALEONTOLOGY
THE UNIVERSITY OF MICHIGAN
CONTRIBUTIONS FROM THE MUSEUM OF PALEONTOLOGY
Director: LEWIS B. KELLUM
The series of contributions from the Museum of Paleontology is a medium
for the publication of papers based chiefly upon the collections in the Museum.
When the number of pages issued is sufficient to make a volume, a title page and
a table of contents will be sent to libraries on the mailing list, and to individuals
upon request. A list of the separate papers may also be obtained. Correspondence
should be directed to the Museum of Paleontology, The University of Michigan,
Ann Arbor, Michigan.
1. Silicified Trilobites from the Devonian Jeffersonville Limestone at the Falls
of the Ohio, by Erwin C. Stumm. Pages 1-14, with 3 plates.
2. Two Gastropods from the Lower Cretaceous (Albian) of Coahuila, Mexico,
by Lewis B. Kellum and Kenneth E. Appelt. Pages 15-22, with 2 figures.
3. Corals of the Traverse Group of Michigan, Part XII, The Small-celled
Species of Favosites and Emmonsia, by Erwin C. Stumm and John H. Tyler.
Pages 23-36, with 7 plates.
4. Redescription of Syntypes of the Bryozoan Species Rhonzbotrypa quadrata
(Rominger), Roger J. Cuffey and T. G. Perry. Pages 3745, with 2 plates.
5. Rare Crustaceans from the Upper Devonian Chagrin Shale in Northern Ohio,
by Myron T. Sturgeon, William J. Hlavin, and Robert V. Kesling. Pages
47-64, with 5 plates.
6. A Fossil Dennstaedtioid Fern from the Eocene Clarno Formation of Oregon,
by Chester A. Arnold and Lyman H. Daugherty. Pages 65-88, with 7 plates.
7. A New Species of Melocrinites from the Middle Devonian Bell Shale of
Michigan, by Robert V. Kesling. Pages 89-103, with 2 plates.
8. A New Spiraculate Blastoid, Pyra?niblastus, from the Mississippian Hampton
Formation of Iowa, by Donald B. Macurda, Jr. Pages 105-1 14, with 1 plate.
9. A Drastic Reappraisal of "Lepidasterella babcocki Schuchert"-as
ter gyalinzls Clarke, a Streptophiuran Auluroid, by Robert V. Kesling. Pages
115-133, with 4 plates.
10. Decadocrinus hughm'ngi, a New Middle Devonian Crinoid from the Silica
Formation in Northwestern Ohio, by Robert V. Kesling. Pages 135-142, with
11. Two New Crinoids of the Family Periechocrinitidae from the Middle
Devonian Thunder Bay Limestone of Michigan, by Robert V. Kesling.
Pages 143-155, with 2 plates.
VOL. XIX, No. 11, pp. 143-155 (2 pls., 2 figs.)
TWO NEW CRINOIDS OF THE FAMILY PERIECHOCRINITIDAE
FROM THE MIDDLE DEVONIAN THUNDER BAY LIMESTONE
ROBERT V. KESLING
Gennaeocrinus romingeri and Corocrinus pettyesi, two distinctive new
crinoids from the Thunder Bay Limestone exposed at Partridge Point,
near Alpena, Michigan, are named for the men who discovered the holo-
types many years ago. Gennaeocrinus rominge~i is distinguished by its
bowl-shaped dorsal cup, pattern of concentric triangles produced by pro-
nounced costae normal to sutures of the cup plates, few IBrBr, in each
interray, smooth tegminal plates except for one central tubercle, and six
arms in each ray formed on axillary PBr,, SBrBr,, and free TBrBr, on
the inner quarter-rays. Corocrinus pettyesi is characterized by basal flanges
on the BB and by very large RR and X, (anal x ) , nearly twice the size of
PBrBr,, provided with double ridges extending onto BB.
Introduction .............................................................. 143
Locality .................................................................. 144
Systematic descriptions .................................................... 144
Literature cited ........................................................... 153
Plates ............................................................ (after) 153
Barris and Wachsmuth (1886), Wachsmuth and Springer (1897), Wood
(1904), Thomas (1920), Springer (1920; 1921), and others, two new
species have been distinguished. When the holotypes were discovered
many years ago, they were not recognized as new nor described. Both
crinoids belong to the family Periechocrinitidae.
Gennaeocrinus romingeri is named in honor of Dr. Carl Ludwig Ro-
minger, who found the holotype, probably in 1898, the year in which he
LTHOUGH CRINOIDS from the Thunder Bay Limestone of Michigan
have been studied for nearly a century and have been described by
144 ROBERT V. KESLING
made extensive collections from the exposure at Partridge Point. Coro-
crinus pettyesi is named in honor of Mr. Leon 0. Pettyes, of Alpena,
Michigan, who discovered the holotype; the specimen may have been part
of an extensive collection of invertebrates obtained from him in 1926.
One additional specimen of Gennaeocrinus romingeri and two of Corocrinus
pettyesi were collected by Mr. Irving G. Reimann in 1945, at which time
he was employed by the Buffalo Society of Natural Sciences and presented
the specimens to the Museum of the Society.
All specimens are fairly well preserved, although the distal parts of the
arms are missing. As deposited in the Museum of Paleontology and the
Buffalo Museum of Natural Sciences, they were partly obscured by weath-
ered matrix. This was removed by careful cleaning with small needles and
Professor Chester A. Arnold and Professor Lewis B. Kellum critically
read the manuscript. Mrs. Helen Mysyk typed the final draft, and Mr.
Karoly Kutasi assisted in photography. My sincere thanks to each for
help in preparing this paper.
Holotypes of both species are deposited and catalogued in the Museum
of Paleontology of The University of Michigan.
All specimens described here are from the same locality.
Bluffs on the northeast side of Partridge Point, a peninsula between Lake Huron and
Squaw Bay, about 4 miles south of Alpena, Michigan, extending from the center
of sec. 11 into its SEg, T. 30N., R. 8E. Type locality of the Thunder Bay
Wachsmuth and Springer 1885
Order MONOBATHRIDA Moore and Laudon 1943
Suborder Tanaocrinina Moore 1952
Superfamily Periechocriniticae Ubaghs 1953
Family Periechocrinitidae Austin and Austin 1843
Genus Gennaeocrinus Wachsmuth and Springer 188 1
kentuckiensis Shumard (1866, p. 345).
original designation ( 188 1, p. 16 1 ), Actinocrinus
Gennaeocrinus romingeri, sp. nov.
(Pl. I, Figs. 1-8)
flat base reminiscent of Megistocrinus, composed of 3 BB, 5 RR, 5 PBrBr,,
bowl-shaped rather than cup-shaped, with a rather
THUNDER BAY CRINOIDS 145
5 PBrBr,, 10 SBrBr,, X, (anal x ) , 3 XX,, 5 XX,, 5 XX,, about 5 XX,,
4 IBrBr,, 8 or 9 IBrBrZ, 12 or 13 IBrBr,, 8 or 9 IBrBr,, and several
ISBrBr and ITBrBr (Fig. 1).
BB forming large regular hexagon, about two-fifths the diameter of
entire cup (PI. I, Figs. 1, 8). Each of the three BB pentagonal, bounded
distally by three RR or by two RR and X, and laterally by two other BB,
ornamented with seven or eight regularly spaced sharp costae normal to
its distal side and three or four normal to each of its distolateral sides
(Fig. 1). Proximal angle of PB modified by a relatively small facet for
articulation with column; margin around facet slightly elevated and
FIG. 1. Gennaeocrinus romingeri, sp. nov. Labeled plate diagram, with pattern of
ornamentation indicated on some rays and interrays.
ROBERT V. KESLING
RR very large, together with the similar X, forming a circlet three-
fourths the diameter of the entire cup. Each R hexagonal; those of C and
D rays (Pl. I, Figs. 4-6) bounded by B, R, IBr,, PBr,, X,, and X,; those of
B and E rays (PI. I, Figs. 3-4, 6-7) bounded by a pair of BB, 2 RR, 2
IBrBr,, and PBr,; that of A ray (Pi. I, Figs. 3, 7) in contact with 1 B,
2 RR, 2 IBrBr,, and PBr,. Each plate ornamented with a thick ridge from
its center to PBr, along the middle of the ray and with regularly spaced
costae normal to each side, about seven or eight extending dorsally onto
B or BB, seven or eight laterally onto adjacent RR or R and X,, five or
six lateroventrally onto IBrBr, or ZBr, and X,, and about four dorsally
onto PBr,; ridge much higher than costae and nearly three times as wide
as each costa.
PBrBr, nearly half as high and two-thirds as wide as RR. Those of
C and D rays (Pl. I, Figs. 4-6) bounded by R, X,, PBr,, IBr,, and IBr,,
hence five-sided; those of other rays bounded by R, 2 ZBrBr,, 2 IBrBr2,
and PBr,, hence six-sided as normal for the genus. Each PBr, ornamented
with a thick median ridge extending from R to PBr2 and with regularly
spaced costae normal to the sides, about four extending onto R, five or
six onto each ZBr,, four or five onto each IBr,, and four onto PBr,.
PBrBr, axillary (Fig. 1); those of the two posterior (C and D) rays
each bordered by PBr,, X,, X,, 2 SBrBr,, ISBr,, and IBr,, hence seven-
sided; those of other rays normally bordered by PBr,, 2 IBrBr,, 2 SBrBr,,
and ISBr,, hence six-sided (subpentagonal except for narrow dorsal contact
with small ISBr,). Each PBr, ornamented with strong ridges in form of Y,
radiating from center to PBr, and SBrBr,, and with a few costae normal
to sides bordering PBr, and IBrBr, or ZBr,, X,, and X,.
SBrBr, axillary (Fig. 1) ; those of half-rays at sides of posterior (CD)
interray each bordered by PBr,, X,, X,, 2 TBrBr,, ITBr,, and ISBr,;
others bordered by PBr,, IBr,, 2 TBrBr,, ITBr,, ISBr,, and (in some)
by IBr,, hence six- or seven-sided. Each SBr, ornamented with pronounced
ridges in form of Y, outlining the branching of the ray.
TBrBr, incorporated in calyx, other TBrBr free. TBrBr, on inner
quarter-rays axillary, so that each ray bears 6 arms (PI. I, Fig. 8).
ISBrBr, very narrow. ITBrBr, small. Other interbrachials small and
irregular, their boundaries indistinct.
IBrBr, about the same size as PBrBr,, normally hexagonal, bordered
by 2 RR, 2 PBrBr,, and 2 IBrBr,. In AB interray of holotype (PI. I,
Fig. 3)) IBr, larger than other IBrBr,, bordered ventrally by 3 IBrBr, and
hence seven-sided. IBr, ornamented by five or six costae normal to each
side, its center raised in a general protuberance.
THUNDER BA 1 ' CRINOIDS 147
Normally two IBrBr, in each interray (Pl. I, Figs. 4, 6-7), but AB
interray of holotype with three IBrBr, (PI. I, Fig. 3). Normal IBr,
septagonal, bordered by IBr,, IBr,, 2 IBrBr,, SBr,, PBr,, and PBr,, orna-
mented with a few costae normal to each side; its central protuberance less
pronounced than that of ZBr,.
Normally only about three IBrBr, in each interray, small, each about
half the size of IBr, (PI. I, Figs. 6-7); four IBrBr, in AB interray of
holotype, displaced upward by enlarged IBr, and three IBrBr, (PI. I,
Fig. 3). Only two or three IBrBr, in each interray. Few IBrBr in the
third and fourth ranges, resulting in very steep walls of dorsal cup (PI. I,
X, (anal x ) very large (PI. I, Figs. 1, 5, 8), the same size and shape
as RR, bordered by B, 2 RR, and 3 XX?. XX, of about equal size, smaller
than ZBrBr, in other interrays; the two lateral XX, each bordered by R,
X,, X,, 2 XX,, PBr,, and PBr,, hence seven-sided; the central X, bordered
by X,, 2 XX,, and 3 XX,, hence six-sided (PI. I, Fig. 5). Five XX, of
about equal size, the lateral plates bordered by PBr, and SBr,. Five XX,
in a narrow band between SBrBr,. Five XX,, very small, extending be-
tween TBrBr,. All plates of posterior interray ornamented with costae
normal to their sides: X, with seven or eight on each side, X, with three
to seven, X, with one to three, and X, and X, with one. Median costa of
interray slightly elevated above general level of costae, as are middle costae
to sides of XX, and XX,, giving them a stellate appearance (Pl. I, Figs.
Dorsal cup terminating at level of TBrBr,, IBrBr,, and XX,, there
encircled by about 35 small plates.
Dimensions of holotype: diameter of cup through I'BrBr, 18.4 mm;
height of cup to top of PBrBr,, 7.0 mm; width of XI, 5.3 mm; greatest
diameter BB circlet, 6.7 mm.
Tegmen.-Tegmen (PI. I, Fig. 2) gently arched, divided into lobate
ambulacral areas by radiating interambulacral channels or grooves. Open-
ings for arms large, proximodistally elongate, set atop tegmen rather than
on beveled junction of dorsal cup and tegmen. Numerous small plates with
indistinct sutures. Anal opening posterior, very near edge of tegmen.
Tegmen nearly smooth, ornamented by very faint crests, apparently
connecting centers of plates. Large central tubercle; no ambulacral spines
or nodes. Column, distal parts of arms, and pinnules unknown.
Remarks.-As shown in Table I, the pattern of branching of the rays
is distinctive in this crinoid, alone sufficient to distinguish it from all other
described Gennaeocrinus species. The bowl-shaped dorsal cup is unusual
ROBERT V. KESLZNG
Pattern of Branching in Rays of Gennaeocrinus Species
In plate diagrams, individual plates indicated only as far as the last axillary plate.
PBrBr* and SBrBr shown in solid black, TBrBr in outline, QBrBr doubly cross-hatched,
and quinque-brachials horizontally ruled.
Branching types are known to occur as follows:
Ehlers (some rays; rays incomplete, perhaps additional bifurcations
were present but not preserved).
Wood, carinatus crassicostatus Goldring, comptus Rowley, comptus
spiniferiis Rowley, facetus Rowley, goldringae Ehlers, peculiaris Goldring (some
C-romingeri, sp. nov.
Hall, nyassa Hall.
for the genus, more closely resembling that of the related Megistocrinus,
but it is approached by Gennaeocrinus kentuckiensis (Shumard) . The
steep walls and flat base are accentuated by the absence of flanges on
the BB. G. romingeri has even costae and three IBrBr, in each interray,
whereas G. kentuckiensis has uneven or interrupted costae and four or five
IBrBr, in each interray. The new species is readily separated from
THUNDER BA Y CRINOIDS
TABLE I (Cont'd)
(Second from mid.)
fi r 2 r 2
Arms per Ray
F--arkonensis Whiteaves, variabilis Kesling and Smith (some rays).
Goldring (A, B, and E rays), variabilis Kesling and Smith (some rays).
J-mourantae Goldring (C and D rays).
G. carinatus Wood and G. carinatus crassicostatus Goldring by the absence
of the flange-like ridges on the BB and spoon-shaped processes on the RR.
UMMP 30519; paratype, BMNS E16586.
Genus Corocrinus Goldring 1923
Type species.-By original designation, Corocrinus ornatus Goldring
(1923, p. 202).
ROBERT V . KESLING
FIG. 2. Corocrinus pettj'esi, sp. nov. Labeled plate diagram, with pattern of
ornamentation indicated on some rays and interrays.
Corocrinus pettyesi, sp. nov.
(Fig. 2 ; P1. 11, Figs. 1-7)
RR and flaring above PBrBr,, composed of 3 BB, 5 RR, 5 PBrBr,,
5 PBrBr,, 10 SBrBr,, X, (anal x), 3 XX,, 5 XX,, 7 XX,, 9 XX,,
4 IBrBr,, 8 IBrBr,, 12 ZBrBr,, and 12 IBrBr, (Fig. 2 ) . Pseudohexameral
symmetry as viewed dorsally (Pl. 11, Figs. 4, 7), with X, equivalent to RR,
median X, to PBrBr,, lateral XX, to IBrBr,, median X, to PBrBr,, and
lateral XX, to IBrBr,.
BB large, equal, flat-based with flanges forming an expanded collar
around the circlet (Pl. 11, Figs. 3, 5-6). As viewed dorsally (Pl. 11, Fig. 7),
vase-shaped (Pl. 11, Figs. 2-3, 5-6), tapering below
THUNDER B.4 Y CRINOIDS
forming a hexagon; as viewed laterally, cuplike, rising above expanded
collar. Each B ornamented with two conspicuous V-shaped ridges (PI. 11,
Figs. 4, 7) ; each V divergent upward from the basal flange, with one
branch normal to the distal border of the plate and the other branch
extending to the distolateral border (Fig. 2) ; a less conspicuous V-shaped
costa within and concentric to each ridge.
RR very large, together with X, forming a cuplike circlet (PI. 11,
Fig. 5). Each R about as high as both PBrBr in the ray, its width three-
fourths the height. RR of A, C, and D rays six-sided, with very long
sutures with adjacent RR or X,, intermediate suture with B, and relatively
short sutures with PBr,, IBr,, and X, or IBr,. RR of B and E rays
seven-sided, their ventral ends broadly acuminate between BB, otherwise
the same size and shape as other RR. From median point about two-thirds
the height from the base, large median ridge extending upward to PBr,,
small ridges to IBrBr, or IBr, and X,, two ridges divergent downward
to B or BB, and a costa normal to each side of the plate. Below and
parallel to this pair of costae, three additional costae on each side; the
upper two reaching the divergent ridges, but the lower one joining a costa
paralleling the divergent ridge to form a narrow triangle around each
R-R-B or R-XI-B junction. BB and RR the most highly ornamented
plates of the cup; as seen dorsally (Pl. 11, Fig. 7), divergent ridges of RR
joined to V-shaped ridges of BB to make a petaliform design. Lateral
costae of RR forming four rings around cup; the upper one complete, the
next two interrupted by the divergent ridges, and the lower one attaining
only the costae parallel to the divergent ridges (PI. 11, Figs. 5-6).
PBr, of each ray narrow, hexagonal, very slightly larger than PBr2.
PBrBr, of C and D rays bordered laterally by X,, X,, IBr,, and IBr,;
those of other rays bordered laterally by 2 IBrBr, and 2 IBrBr,. Each
plate with a broad median ridge occupying over half the PBr,-PBr, suture
and lesser ridges radiating from the center to each of the sides.
PBr, of each ray septagonal, its height and width nearly equal. Plates
of C and D rays bordered laterally by X,, X,, IBr,, and IBr,; others
bordered laterally by 2 IBrBr, and 2 IBrBr,. Each PBr, ornamented
with a broad Y-shaped ridge along the branching of the ray and with small
ridges to other adjacent plates.
SBrBr, of each ray in contact, no intervening ISBr; each about three-
fourths the size of PBr,, laterally bordered by IBrBr of the third and
fourth ranges or by XX of the fourth and fifth ranges. Plates roughly
hexagonal, shape somewhat variable. No plates known beyond SBrBr,, but
plates not axillary.
152 ROBERT V. KESLING
IBr, of each interray about the same size as an adjacent PBr,,
hexagonal, bordered by 2 RR, 2 PBrBr,, and 2 IBrBr,, ornamented with
radiating small ridges normal to each side.
IBrBr, hexagonal, the two of each interray equal, bordered by IBr,,
PBr,, PBr,, 2 ZBrBr,, and the opposite IBr,. IBrBr, about two-thirds the
size of IBr,, higher than wide; higher IBrBr plates decreasing gradually
in size, occupying narrow interray area with sides subparallel above
IBrBr,. Small ridges radiating from centers to sides of plates, becoming
fainter in upper ranges. Median IBr, pentagonal, followed by hexagonal
median IBr, and IBr,; lateral IBrBr, and IBrBr, hexagonal (Fig. 2).
XI (anal x ) large, with the same size, shape, and pattern of orna-
mentation as RR of B and E rays; forming a high circlet with RR.
The median ridge leading upward through the anal series much narrower
than the corresponding median ridge in RR. Median X, considerably
smaller than PBr, of each ray, about half the height of XI, hexagonal,
its width less than its height. Lateral XX, about the same size as PBrBr,,
hexagonal, higher than wide, each bordered by R, XI, X,, 2 XX,, and PBr,.
Five XX, in zigzag range; median X, octagonal, higher than wide, slightly
smaller than median X,, bordered by X, below, X, above, and 2 XX, and
4 XX, at the sides; outer X, slightly smaller, hexagonal, bordered by
2 PBrBr of the adjoining ray, X,, X,, and 2 XX,; intermediate X,
smaller yet, pentagonal, bordered by 2 XX,, 2 XX,, and X, (Fig. 2).
Seven XX, in zigzag range, all hexagonal; median X, smaller than any X,.
Nine XX, in irregular range, the outermost bordered by SBr,, the next
inserted among 3 XX,, and the median X, hexagonal. Other XX small
and irregular. Median ridge of the posterior interray larger than other
ridges; XX plates ornamented with ridges radiating from centers to sides,
decreasing upward and becoming indistinct at about the fifth range.
Dimensions of holotype: height from BB to top of SBrBr,, 18.7 mm;
diameter of BB circlet just above basal ridge, 5.0 mm; diameter of cup at
RR-PBrBr, level, 12.0 mm (mean) ; height of RR and XI, 7.0 mm (mean).
Remarks.-This species can be distinguished from the type species,
Corocrinus ornatus Goldring (1923, pp. 203-5, PI. 26, Figs. 2-4, Text-fig.
47), from the Middle Devonian Ludlowville Formation of New York, by
its much larger RR and X,, parallel rings of costae around the RR-XI
circlet, collar-like ridge on the BB, and narrower interrays.
UMMP 30529; paratypes, BMNS E16585a-6.
THUNDER BAY CRINOIDS
BARRIS, W. H., and WACHSMUTH, CHARLES. 1886. Descriptions of Some New Crinoids
from the Hamilton Group. Proc. Davenport Acad. Sci., Vol. 4, pp. 95-104
(Adv. publ. 1885).
GOLDRING, WINIFRED. 1923. Devonian Crinoids of New York. N.Y. State Mus.,
Mem. 16, 670 pp., 60 pls.
SHUMARD, B. F. 1866. Catalogue of Palaeozoic Fossils. Trans. Acad. Sci. St. Louis,
Val. 2, No. 2, pp. 334-407 (Publ. from 1861-68).
SPRINGER, FRANK. 1920. Crinoidea Flexibilia. Smithsonian Instit. Publ. 2501, 486 pp.,
76 pls., 51 text-figs.
1921. The Fossil Crinoid Genus Dolatocn'nus and Its Allies. U. S. Nat. Mus.
Bull. 115, 78 pp., 16 pls.
THOMAS, A. 0. 1920. Echinoderms of the Iowa Devonian. Iowa Geol. Survey,
Vol. 29, pp. 387-567, Pls. 29-54, Figs. 55-80.
WACHSMUTH, CHARLES, and SPRINGER, FRANK. 1881. Revision of the Palaeocrinoidea.
Proc. Acad. Nat. Sci. Phila., Vol. 33, pp. 177-411, Pls. 17-19 (other parts
issued: 1879, Vol. 31, pp. 226-378, Pls. 15-17; 1885, Vol. 37, pp. 225-364,
PIS. 4-9 ; 1886, Vol. 38, pp. 64-226).
1897. North American Crinoidea Camerata. Mem. Mus. Comp. Zool.,
Vols. 20-21, Atlas, 359 pp., 83 pls.
WOOD, ELVIRA. 1904. On New and Old Middle Devonic Crinoids. Smithsonian Misc.
Coil., Vol. 47, NO. 1467, pp. 56-84, PIS. 15-16.
Manuscript submitted July 3, 1964
ROBERT V. KESLING
EXPLANATION OF PLATE I
(Figures X 3, except as noted)
Gennaeocvinus romingeri, sp. ncv. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
FIGS. 1-2. Dorsal (basal) and ventral (tegminal) views of holotype, UMMP
30519. In each view, posterior (CD) interray uppermost.
FIGS. 3-5, 7. Inclined lateral views of holotype centered on AB, BC, CD, and A E
interrays. The AB interray (Fig. 3) contains 3 IBvBr2, in contrast to other inter-
rays which have only 2 plates.
FIG. 6. Lateral view of holotype centered on DE interray.
FIG. 8. Dorsal (basal) view of paratype, BMNS E16586, X 2. The CD interray is
at the right. The A ray shows axillary TBv3. Facet for articulation with column
is depressed in BB circlet.
THUNDER BAY CRINOIDS
EXPLANATION OF PLATE I1
(All figures X 3)
Corocrinus pettyesi, sp. nov. . . . . . .. . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 150
1. Lateral view of paratype, BMNS E16585a, an incomplete cup. The inter-
ray at the right has 4 IBvBra, one of which is very small.
2-4. Two lateral and dorsal (basal) views of paratype, BMNS E16585b.
This specimen was deeply sculptured in what would seem to have been a clean-
ing attempt by some previous investigator. As a result, it is impossible to identify
5-7. Two lateral and dorsal (basal) views of holotype, UMMP 30529. The
posterior (CD) interray is on the right side of Figure 5. The crinoid is unknown