ECHINODERMATA - KU ScholarWorks - University of Kansas

82 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
aboral side of the anal opening and abuts against the adjacent
radial limbs. The cryptodeltoids are partially exposed
externally and therefore a paired anispiracle occurs
on the anal side. Thus, one paired anispiracle and four
paired spiracles are recognized, a total of five paired
spiracles around the oral opening.
Ambulacra five, short, linear, each 15 mm. long by
1.5 mm. wide, with lancet covered by side plates, and 22
side plates in a space of 10 mm. along an ambulacrum.
Side plates poorly preserved but appearing to be normally
disposed. The surfaces of calyx plates are worn but the
ornamentation appears to consist of fine growth lines subparallel
to plate margins.
Occurrence.—Upper Mississippian, Salem Limestone,
Ellettsville, Indiana.
Type.—Holotype, 6,323, one specimen, Gurley collection,
Walker Museum, University of Chicago.
METABLASTUS WORTHENI (Hall)
Plate 50, figures 4-9; text-figs. 161-163
Pentremites wortheni HALL, 1858, p. 606, pl. 15, fig. 1.
Description.—Calyx calcitic, 16 mm. long by 7.5 mm.
wide, bipyramidal in side view, with flat summit and flat
triangular base, pentagonal in oral view, with periphery
well above mid-height at radial lips. Vault 6.5 mm.
long, pelvis 9.5 mm. long, and pelvic angle 30 degrees.
Stem impression appears to be round, about 1 mm. in
diameter, crenellar, with small round lumen, resting on
the flat triangular aboral surface. Basal circlet long,
rounded pentagonal in basal view, 5 mm. long by 5 mm.
wide, triangular at base, with three normally disposed
basals, each of which has a high, wide ridge extending
down the mid-line from the aboral end. The ridge on
the azygous basal bifurcates at half the distance upward
adorally, each resulting ridge extending to the
radial lips of the "A" and "B" ambulacra, respectively.
The ridge on each of the other two basais trifurcates, with
the median ridge of each extending to the radial lips of
the "C" and "E" ambulacra, respectively, and the lateral
ridges extending to the lips of the "A," "B," and "D"
ambulacra, respectively. These broad ridges give a bulge
or flare to the pelvis in the region of the basiradial sutures,
and are prevalent in the specimens of various species
of Metablastus that occur in the Keokuk, Warsaw,
and Salem formations. Radials five, each 10 mm. long
by 3.5 mm. wide, broadly quadrangular in side view,
with narrow, deep sinus 5 mm. long by 2 mm. wide;
radials overlapping deltoids.
Deltoids four, short, not visible in side view, each
notched at the adorai end by a V-shaped paired spiracle,
with deltoid lips and lancet stipes adjacent to oral opening.
On the anal side there are four deltoids—a superdeltoid,
two cryptodeltoids, and a hypodeltoid. The superdeltoid
is adjacent to the oral opening, with two internal
septa on its aboral surface separating the hydrospire canals
or anal spiracles from the anal opening. Resting on these
two septa are the two cryptodeltoids, which are overlapped
by the adorai ends of the adjacent radial limbs.
The pentagonal hypodeltoid abuts against the radial
limbs, covers the cryptodeltoids, and covers the aboral part
of the anal opening. The cryptodeltoids are partially exposed
and therefore a paired anispiracle is formed on the
anal side. Thus, the oral opening is surrounded by five
openings, consisting of four paired spiracles and an anal
paired spiracle or paired anispiracle.
Ambulacra five, linear, each 7 mm. long by 1 mm.
wide, with lancet completely covered by side plates, one
pore between side plates along deltoid and radial margins,
and 34 side plates in a space of 10 mm. along an ambulacrum.
Side plates normally disposed. There are four or
five hydrospire folds on each side of an ambulacrum. The
surfaces of the calyx plates are ornamented by fine growth
lines subparallel to plate margins .
Occurrence.—Upper Mississippian, Warsaw Limestone,
Boonville, Missouri.
Types.—Plesiotypes, four specimens, purchased from
Wards 6-21-41, Buffalo Society of Natural Sciences, Buffalo,
New York.
Genus MONADOBLASTUS Fay, n. gen.
Type-species, by original designation.—Monadoblastos granulosus
FAY, n. sp.
Generic diagnosis.—Spiraculate blastoids with nine
spiracles, or eight spiracles and an anispiracle, with
anispiracle between epideltoid and hypodeltoid plates,
with hydrospire plates bearing approximately two
pores to each side plate along radial margins, pores
absent along deltoids, lancet covered by side plates
except near adorai end, one hydrospire fold on each
side of an ambulacrum, radials overlapping deltoids,
base concave, and form of calyx elliptical. Mississippian,
New Mexico.
Remarks.—The genus Monadoblastus was probably
derived from Tanaoblastus by reduction of the
hydrospires to one and invagination of the basal circlet.
MONADOBLASTUS GRANULOSUS Fay, n. sp.
Plate 37, figures 1-3, 10; text-figs. 164-167
Description.—Calyx calcitic, suboval in side view, subpentagonal
in oral view, 5 mm. long by 4 mm. wide,
with flat summit, concave base, and periphery at midheight.
Stem round, about 0.5 mm. in diameter, impression
poorly preserved. Basal circlet pentagonal in
aboral view, 1.25 mm. in diameter, with three normally
disposed basal plates. Radials five, each broadly pentagonal
in side view, recurved in basal concavity, 4 mm.
long by 2.5 mm. wide, with radial sinus 4 mm. long by