ECHINODERMATA - KU ScholarWorks - University of Kansas

86 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
angle 180 degrees, base flat, and summit flat. Stem round,
0.75 mm. in diameter, crenellar, with small round central
lumen. Basal circlet 1.5 mm. in diameter, pentagonal in
aboral view, confined to small aboral surface, with three
normally disposed basais. Radials five, each 2.5 mm.
long by 2.5 mm. wide, recurved onto aboral surface,
with short sinus 1 mm. long by 1 mm. wide. Deltoids
overlap radials.
Deltoids four, each 9 mm. long by 4 mm. wide, with
smooth triangular middle portion 2.5 mm. wide at base
along radiodeltoid suture, bordered on either side by
lenticular portions that have aligned lobes even with each
side plate, each row slanting at an angle of about 100
degrees, measured from the mouth as origin and the line
of the food groove as base. The disposition of the anal
plates are the same as in Nucleocrinus elegans. In two
specimens, one polished, one with orals removed, the
hidden superdeltoid was seen. There are two hydrospire
folds on each side of an ambulacrum, with a short hydrospire
canal.
Ambulacra five, linear, recurved below, each 11 mm.
long by 1 mm. wide, with lancet covered by side plates,
and 36 side plates in a space of 10 mm. along an ambulacrum.
Side plates disposed as in Nucleocrinus elegans.
Orals five, subtriangular, covering peristome, interambulacral
in position, and arranged as in Nucleocrinus ekgans.
Occurrence.—Middle Devonian, coral zone of Widder
beds, Hungry Hollow Formation, near Thedford and
Arkona, Ontario.
Types.—Plesiotypes, 3,662, 3,662a (used for above
description), two specimens, from Thedford, Geological
Survey of Canada, Ottawa; 102,707, one specimen, from
tile yard, Thedford, Charles Southworth collection, U. S.
National Museum, Washington; E148, three specimens,
one polished, from Thedford, and E8,244, one specimen,
from tile yard, Thedford (identified as N. lucina), Southworth
collection (1933), E15,939, two specimens, from
tile yard, Thedford, Southworth collection (1943), and
E21,120, nine specimens, from tile yard, Thedford and
Hungry Hill, Arkona, Southworth collection, Buffalo
FIGURE 178. Nucleocrinus meloniformis (BARRis), Middle
Devonian, Hamilton Group, Moscow, New York
(Buffalo Soc. Nat. Sci., no. E8,244); aboral view of basais
and adjoining plates, showing ridges, X15. [Explanation.
—"A," amb.; Z, azygous basal.]
Society of Natural Sciences, Buffalo, New York. All these
specimens, except one, have been labelled as Nucleocrinus
elegans and obviously are misidentified.
Genus ORBITREMITES Austin & Austin, 1842
Type-species, by subsequent designation (Bather, 1899).—Pentremites
derbiensis SOWERBY, 1825.
Generic diagnosis (emend. FAY, 1960).—Spiraculate
blastoids with five spiracles, or four spiracles in
addition to an anispiracle, with a superdeltoid, two
FIGURES 179-187. Species of Orbitremites AUSTIN & AUSTIN, Lower Carboniferous, England.
179-182. 0. derbiensis (SowERBy), Middle Limestone,
Yorkshire (H. H. Beaver coll., nos. 4, 328); 179, summit
and anal areas (no. 328), X15; 180, anal area of acidetched
specimen, X15; 181, cross section of "E" ambulacrum,
oral view (no. 4), X15; 182, part of "E" ambulacrum,
showing side plates (no. 4), x45. 183-185. 0.
cam panulatus (M'CoY), "Devonshire [ ?Derbyshire],
England (Univ. Chicago, no. 1,633); 183, basal area,
X15; 184, cross section of "D" ambulacrum, oral view,
X15; 185, part of "E" ambulacrum, showing side plates,
X45.-186, 187. 0. ellipticus (SowERsy), Clitheroe
Limestone, Yorkshire (H. H. Beaver coll.); 186, summit
area, X15; 187, part of "A" ambulacrum, showing side
plates, X45. [Explanation.—"A," amb.; An, anal opening;
Bf, brachiolar facet; Bp, brachiolar pit; "C," amb.;
C, canal (radial); CR, cryptodeltoid; "D," amb.; D, deltoid;
H, hydrospire; HD, hypodeltoid; HP, hydrospire
plate; L, lancet; 0, oral opening; OSp, outer side plate;
P, pore; Pf, pore furrow; S, spiracle; Sp, main side plate;
Su, superdeltoid; Z, azygous basal.]