ECHINODERMATA - KU ScholarWorks - University of Kansas

76 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
gins. Radials five, each hexagonal in side view, 5 mm.
long by 3.5 mm. wide, with shallow sinus 4 mm. long by
1.5 mm. wide, with growth striae subparallel to margins.
Deltoids overlap radials.
Deltoids four, lancet-shaped, each 3 mm. long by 2 mm.
wide, notched at the adorai tip by two spiracles along
ambulacral margins. On the anal side there are ?two
deltoids; a horseshoe-shaped or V-shaped ?epideltoid
adjacent to the oral opening, curving around the adorai
part of the anal opening on three sides, and a large
lancet-shaped hypodeltoid on the aboral side of the anal
opening, extended ventrally into a hood or coronal process.
Two cryptodeltoids may be present. The anal
spiracles or hydrospire canals are separated internally
from the anal opening by deltoid septa, but externally
only one anispiracle is visible. Thus there are nine openings
around the oral opening, consisting of eight spiracles
and the anispiracle. There are three hydrospire folds on
each side of an ambulacrum.
Ambulacra five, broadly linear, each 7.5 mm. long
by 1.5 mm. wide, each lancet plate being exposed onethird
or more of its width along the middle of each
ambulacrum. The side plates are normally disposed, with
30 side plates in a space of 10 mm. along an ambulacrum,
one pore between adjacent side plates notched in the
deltoid and radial ambulacral margins, and three main
cover-plate sockets to each side plate along the main food
groove. In addition to fine growth striae, the calyx plates
are ornamented by coarse ridges subparallel to the plate
margins.
Remarks.—The type specimens are grouped together
in two glass vials and it has not been possible to find all
of the figured specimens. There are 37 specimens in all,
including the holotype; the above description applies to
specimen RX-134h. The other specimens resemble this
one closely and all belong to the same species.
Occurrence.—Lower Mississippian, lower Burlington
Limestone, in chert, Louisiana, Missouri.
Types.—Holotype, RX-134; paratypes, RX-134a-i (36
specimens). Holotype unfigured but almost same as
134h, herein figured on pl. 45, figs. 1-3. RX-134a, Row-
LEY (1901), pl. 28, fig. 8, herein figured on pl. 45, figs.
4, 6, 8. RX-134b, polished section showing hydrospires.
RX-134c shows area of stem attachment. RX-134d, Row-
LEY & HARE (1891), pl. 3, fig. 17, refigured by ROWLEY
(1901), pl. 28, fig. 5, herein figured on pl. 45, fig. 7.
RX-134e, ROWLEY (1900), pl. 2, fig. 18. RX-134f, Row-
LEY (1901), pl. 28, figs. 6-7. RX-134g, 18 unfigured types.
RX-134h was provisionally selected as lectotype until recently
when the holotype was found. RX-134i, 11 specimens
in a glass vial, with the holotype. Rowley collection,
Department of Geology, University of Illinois.
Genus MESOBLASTUS Etheridge & Carpenter, 1886
Type-species, by original designation.—Pentatrematites crenulatus
ROEMER, 1851.
Generic diagnosis.—Spiraculate blastoids with nine
spiracles or eight spiracles and an anispiracle, with
superdeltoid, two cryptodeltoids, and hypodeltoid on
the anal side, and three hydrospire folds on each side
of an ambulacrum; thick hydrospire plate present; approximately
five hydrospire pores to each side plate
infolded into a double row; lancet covered by side
plates except at adoral end; pores absent along deltoid
margins; radials overlapping deltoids; calyx form subglobular.
Lower Carboniferous, Belgium, England,
Germany.
Remarks.—The genus Mesoblastus may have been
derived from a form similar to Pentremitella, but until
the latter is better understood this is only a guess.
Pentremitella appears to have characters similar to
Schizotremites but the latter is not well understood
at present.
MESOBLASTUS CRENULATUS (Roemer)
Plate 47, figures 1-13; text-figs. 151-157
Pentatrematites crenulatus ROEMER, 1851, p. 366, pl. 4, figs. 15a-d.
Description.—Calyx calcitic, subglobular in side view,
rounded pentagonal in top view, 6 mm. long by 7.5 mm.
wide, with flattened summit, flat to slightly convex base,
and periphery below mid-height. Stem round, 0.75 mm.
in diameter, on raised hexagonal area of basais, with
about 30 crenellae extending almost to central round
lumen. Basal circlet pentagonal in aboral view, slightly
EXPLANATION OF PLATE 23
FIGURE
PAGE
1 -3. Cordyloblastus gilbertsoni (ETHERIDGE & CARPENTER),
plesiotype, 313, Schultze coll., Harvard Mus. Comp.
Zoology; Middle Devonian, Pelm, Germany; oral, "D"
ambulacral, aboral views of a specimen that closely resembles
calyx figured by Schultze (1867, pl. 13, fig. 7c). 57
4-8. Cordyloblastus acutangtdus (ScHuurzE), holotype, 325,
Schultze coll. (labelled type), Harvard Mus. Comp.
Zoology; Middle Devonian, Eifel, Pelm, Germany; 4-6,
oral, "D" ambulacral, aboral views of a specimen exactly
like type figured by Schultze (1867, pl. 13, fig. 6) ( X2.5)
[another specimen in the same tray is identical with
Scum..-rzE's, fig. 6c; the summit of this specimen .1 ground
and polished]; 7, detail view of oral area of specimen
shown in fig. 4 ( X10.5); 8, detail view of "B" ambulacrum
showing pores between plates along raised ambulacral
margins and lancet completely covered by side plates
( X 10.6) 54