ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 69
and a separate anus. The oral area is covered by approximately
18 oral plates, consisting of five large orals in the
center, each arrow-shaped and interambulacral in position,
bordered aborally by 12 or 13 accessory orals. There
are two accessory orals at the adorai end of each ambulacrum,
and two or three (one of which may be a superdeltoid)
on the anal side. It is assumed that two hydrospire
folds occur on each side of an ambulacrum.
Ambulacra five, linear, raised, recurved below, each
19 mm. long by 1 mm. wide, with lancet covered by side
plates, 26 side plates in a space of 10 mm. along an ambulacrum,
and side plates disposed as in Nucleocrinus.
There is one large pore between adjacent side plates along
the deltoid and radial margins, and four cover-plate
sockets to each side plate along the main food groove.
Inner side plate present. The surfaces of the calyx plates
are ornamented as in Nucleocrinus by fine growth striae
parallel to plate margins, with small aligned granules or
ridges on deltoid and cryptodeltoid ambulacral margins,
each ridge corresponding in position to one pore, aligned
at a high angle to ambulacral margins.
Occurrence.—Middle Devonian, Onondaga (Columbus)
Limestone, Columbus, Ohio.
Types.—Syntypes, 1,317, two specimens, University
of Cincinnati Museum. Syntypes, 6,114, two specimens,
Gurley collection, illustrated by GURLEY (1894), p. 63,
pl. 8, fig. 26-30, Walker Museum, University of Chicago.
Genus ELEUTHEROCRINUS Shumard &
Yandell, 1856
Type-species, by original designation (monotypy).—Elefitherocrinus
cassedayi SHUMARD 8c YANDELL, 1856.
Generic diagnosis.—Spiraculate blastoids with five
spiracles, or four spiracles and an anispiracle, with
superdeltoid, two cryptodeltoids, and a hypodeltoid
on anal side, six or seven hydrospire folds on each side
of an ambulacrum, lancet covered by side plates, with
one pore between adjacent side plates along deltoid
and radial margins, radials overlapping deltoids, calyx
plates irregular because of shortened "D" ambulacrum;
ellipsoidal in side view. Devonian, Kentucky,
Indiana, New York, Ontario.
Remarks.—The genus Eleutherocrinus was probably
derived from Hyperoblastus by complete closure
of the sinus areas, shortening of the (D) ambulacrum,
and consequent shifting of calyx plates.
ELEUTHEROCRINUS CASSEDAYI
Shumard & Yandell, 1856
Plate 26, figures 1-8; plate 27, figures 1-11; text-figs. 126-137
Eleutherocrinus cassedayi SHUMARD & YANDELL, 1856, p. 74, pl. 2,
figs. 1-5.
Description.—The new holotype (neotype) is 18 mm.
long by 9 mm. wide, vault 14 mm. long, pelvis 4 mm.
long, pelvic angle 70 degrees in left anterior radial view
and 85 degrees in anterior radial view. The basal circlet
is irregular, with two equal long basals 9 mm. long by
3 mm. wide extending upward on the "D" ambulacral
side, azygous basal confined to the base, 3 mm. long by
2 mm. wide. The base of the azygous plate has a smooth
area about 0.5 mm. from the aboral tip, in which a
seemingly round crenellar depression occurs, too illdefined
for positive identification. Apparently a stem is
absent. A single prominent ridge extends downward on
the middle face of each basal, that on the azygous basal
splitting and extending to the lips of the "A" and "B"
radials, whereas the other two extend to the "C" and
"E" radial lips, respectively. The ridges on the two
equal basais each branch and have an extension up the
middle of the plate, parallel to the interbasal suture.
Radials five, irregular in shape and length. The "A,"
"B," "C," and "E" radials are 16 mm. long, the "A" and
"B" radials being symmetrical, 5 mm. wide, with sinus
13 mm. long, whereas the "C" and "E" radials are unsymmetrical,
with narrow pointed limbs on the "D"
side, each 6 mm. wide, with sinus 14 mm. long. The
sinus areas are approximately 1 mm. wide. The "D"
radial is short and wide, roughly subquadrangular, 9 mm.
long and 7 mm. wide, with short, wide sinus confined
to the summit; radials overlapping deltoids.
The "AB," "BC," and "EA" deltoids are short, visible
in side view, 1 mm. long, triangular, with depressed
deltoid septum, and each with a spiracle between the
deltoid body and deltoid lip. The "DE" deltoid is short,
quadrangular, confined to the summit, and smaller than
the other deltoids, but with similarly formed spiracle. On
the anal side there are four deltoid plates. The super-
EXPLANATION OF PLATE 20
FIGURE
1-9. Cordyloblastus clavatus (ScHut.TzE). 1 3,8. Syntypes,
539, Schultze coll., Harvard Mus. Comp. Zoology; Devonian,
near Kerpen, Nollenbach, Germany; 1-3, oral, "A"
ambulacral, aboral views ( X4.9); 8, polished cross section
of "E" ambulacrum looking aborally ( X3).
4-6,9, plesiotype, 19,090, Gurley coll., Univ. Chicago;
PAGE
Calizas de Arnao, Le6n, Spain; 4-6, oral, "D" ambulacral,
aboral views of specimen with polished summit ( X5.2);
9, enlarged view of fig. 4 ( X7.7). 7. Plesiotype,
S3,6I3, Springer coll., U.S. Natl. Mus.; Lower Devonian,
Calizas de Arnao, Sabero (Le6n), Spain; "D" ambulacral
view (X6.5) 54