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60 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
Genus CRIBROBLASTUS Hambach, 1903
Type-species, by subsequent designation (Bass ler, 1938).—Pentremites
cornutus MEEK & WORTHEN, 1861.
Generic diagnosis.—Spiraculate blastoids with
eight spiracles in addition to anispiracle, which is
located between epideltoid and hypodeltoid, two hydrospire
folds on each side of an ambulacrum, lancet
covered by side plates with single pore between side
plates along radial and deltoid margins, hydrospire
plate present, radials overlapping deltoids, deltoids
with high coronal processes; calyx ellipsoidal in side
view. Mississippian, Illinois, Missouri.
Remarks.—The genus Cri broblastus may have
been derived from a form similar to Carpenteroblastus
in which the deltoids developed coronal processes, the
pores remained simple, and the base became concave.
CRIBROBLASTUS CORNUTUS (Meek & Worthen)
Plate 46, figures 6-11; text-figs. 95-97
Pentremites cornutus MEEK & WORTHEN, 1861, p. 141.
Granatocrinus cornutus (MEEK & WORTHEN), 1866, p. 276, pl. 20,
fig. 1.
Description.—Calyx calcitic, subspherical, with concave
base, rounded summit, 13 mm. long by 12 mm.
wide, periphery near mid-height, and adoral ends of
deltoids extended into high coronal processes. Stem not
visible. Basal circlet small, hidden in basal concavity, 2
mm. wide. Radials five, each elongate hexagonal, 10 mm.
long by 7 mm. wide, strongly recurved below in basal
concavity, with broad shallow sinus 10 mm. long by 3
mm. wide, limbs flared into broad raised ridges; radials
overlapping deltoids.
Deltoids four, arrow-shaped, each 5 mm. long by 3
mm. wide by 3 mm. high, the adoral tips of each extended
ventrally into a high hornlike coronal process.
Two spiracles are found on the adorai end of each deltoid,
separated by a wide medium septum at the marginal
base. On the anal side the large oval anispiracle is
located between a small adorai epideltoid and a large
pentagonal aboral hypodeltoid. Two hydrospire folds
occur on each side of an ambulacrum, with a hydrospire
plate, but only a single pore between side plates along the
radial margins. Pores are present along the deltoid margins.
Ambulacra five, linear, each 13 mm. long by 1-1.25
mm. wide, lancet covered by side plates, and 30 side
plates in space of 10 mm. length along an ambulacrum.
Side plates and pores normally disposed, with one large
pore between adjacent side plates along radial and deltoid
margins of ambulacra. The surfaces of the calyx plates
are worn smooth.
Occurrence.—Upper Mississippian, St. Louis Limestone,
Brown County, Illinois (holotype); ?Warsaw
Limestone, Fenton, Missouri (plesiotypes).
Types.—Holotype, X-361, specimen in rock, Illinois
State Museum, old no. 10,058, Department of Geology,
University of Illinois, Urbana. The above description is
primarily based on this specimen. Plesiotypes, S3,771, 13
specimens in three slabs of rock (one slab cut and polished),
Springer collection, U. S. National Museum,
Washington.
Genus CRYPTOBLASTUS Etheridge & Carpenter,
1886
Type-species, by original designation.—Pentremites melo OWEN &
SHUMARD, 1 850.
Generic diagnosis.— Spiraculate blastoids with
eight spiracles in addition to anispiracle, located between
epideltoid? and hypodeltoid, possibly with two
deep cryptodeltoids, lancet exposed along middle onethird
of its width except near aboral end, two hydrospire
folds on each side of an ambulacrum, hydrospire
plate present, pores absent along deltoid margins,
radials overlapping deltoids except at extreme adorai
tip of the radial limbs where deltoids project slightly
over the radials, base slightly concave; calyx ellipsoidal
in shape, with depressed interradial sutures. Mississippian,
Iowa, Missouri.
Remarks.—The genus Cry ptoblastus was probably
derived from Tanaoblastus by slight overlap of deltoids
on adorai tips of radial limbs, the interradial sutures
having been depressed, and the base becoming
concave.
EXPLANATION OF PLATE 15
FIGURE
PAGE
1-2. Orophocrinus conicus WACHSMUTH & SPRINGER, metatypes,
S3,226, Springer Coll., U.S. Natl. Mus.; Lower Mississippian,
Kinderhook Group, Le Grand, Marshall County,
Iowa; I, side view (X3); 2, side view of another specimen
(X2.6) 37
3-8. Orophocrinus fusiformis (WAcHsmin-H & SPRINGER),
metatypes, S3,226 (fig. 3), S3,227 (figs. 4-8), Springer
coll., U.S. Natl. Mus.; Lower Mississippian Kinderhook
Group, Le Grand, Marshall County, Iowa; 3, side view of
specimen ( X3.6); 4, side view of another specimen
( X2.2); 5, side view of another specimen ( X2.5); 6,
side view of another specimen ( X3); 7, side view of another
specimen (X2.5); 8, detail view of an ambulacrum
of specimen shown in fig. 7 ( X14.6) 37