ECHINODERMATA - KU ScholarWorks - University of Kansas

78 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
of an ambulacrum, extending a long distance down
the sides of the radial limbs.
METABLASTUS LINEATUS (Shumard)
Plate 19, figures 6-8; text-figs. 158-160
Pentremites lineatus SHUMARD, 1858, p. 241, pl. 9, figs. 3a-b.
Description.—The new holotype (neotype) is 33 mm.
long by 12 mm. wide, vault 13 mm. long, pelvis 20 mm.
long, pelvic angle 25 degrees, and shape of calyx in side
view elongate conical, with truncated summit. Pentagonal
in top view. Basal circlet conical in side view,
10.5 mm. long, with three normally disposed basals.
Radials 22 mm. long, overlapping deltoids. Deltoids not
visible in side view except where seen along ambulacral
margins.
Deltoids four, triangular, confined to summit, each
with a paired spiracle at its adoral tip. On the anal side
there are four deltoid plates, a superdeltoid occurring next
to the oral opening with two elongate cryptodeltoids, each
2 mm. long resting on it and adjacent radial limbs projecting
over them. The pentagonal hypodeltoid, 4 mm.
long by 3 mm. wide, rests on the cryptodeltoids and abuts
against the adjacent radial limbs. A paired anispiracle is
present on the anal side; thus five paired spiracles occur
on the summit (or four spiracles in addition to a paired
anispiracle). Four hydrospire folds are seen on each side
of an ambulacrum.
Ambulacra five, linear, each 13 mm. long by 1 mm.
wide, with lancet covered by side plates, and 24 side
plates in a length of 10 mm. along an ambulacrum, with
four cover-plate sockets to each side plate along ambulacral
groove. The ambulacra are set deep within narrow
sinus walls. The side plates are normally disposed, with
one pore between adjacent side plates along the deltoid
and radial margins. The radial plates are thin, and the
hydrospires extend almost the length of the ambulacra.
The surfaces of the calyx plates are ornamented by fine
growth lines parallel to plate margins.
Renzarks.—The type specimen was probably destroyed
and therefore a new holotype and paratype have been
herein selected, described above.
Occurrence.—Lower Mississippian, upper part of Burlington
Limestone, Sagetown, Illinois.
Types.—Neotypes, S4,958 (new holotype), and
S4,957 (new paratype), Springer collection, old no. S3,628
(holotype in slab and paratype a cut section), U. S. National
Museum, Washington.
148
149
FIGURES 147-150. Lophoblastus inopinatus (RowLEy &
HARE), Lower Mississippian, Burlington Limestone,
Louisiana, Missouri (Univ. Illinois, no. RX-134h).
147. Summit area, X15. 148. Basal area, X15.
149. Cross section of ambulacrum, X15. 150. Part
of "A" ambulacrum, showing side plates, X45. [Explanation.—An,
anal opening; Bf, brachiolar facet; Bp, brachiolar
pit; C, canal (radial); D, deltoid; ED, epideltoid;
HD, hypodeltoid; L, lancet; 0, oral opening; P, pore
Pf, pore furrow; S, spiracle; Sp, main side plate; Z, azygous
basal.]