ECHINODERMATA - KU ScholarWorks - University of Kansas

68 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
periphery above mid-height, with flat summit and small
deep basal concavity. Stem round, crenellar, 2 mm. in
diameter, with small round lumen. Basal circlet pentagonal
in aboral view, 3.5 mm. wide, concave, in deep
basal concavity, with three normally disposed basais, each
with a prominent central ridge. Radials five, pentagonal
in side view, each 8.5 mm. long by 9 mm. wide, sharply
recurved below, with body in basal concavity, with narrow,
shallow sinus 5 mm. long by 1.25 mm. wide, and
body flaring at radial lips. Deltoids overlap radials. The
surfaces of the radials and basais are ornamented by fine
growth striae subparallel to plate margins.
Deltoids four, broadly lenticular, each 32 mm. long
by 15 mm. wide, with two hemielliptical spiracles notched
in the adorai tip adjacent to the ambulacral margins. On
the anal side there are at least three anal deltoid plates
and possibly four exposed. The two cryptodeltoids extend
around the sides of the anal opening and are separated
by one or two oral plates on the adorai side of the
anal opening. The plate adjacent to the anal opening
may be a superdeltoid plate. The long quadrangular hypodeltoid,
bordered on either side by the cryptodeltoids,
is aboral to the elongate diamond-shaped anal opening,
and has a low rounded anal lip that rapidly decreases in
height aborally. The adorai tip of each cryptodeltoid has
a hemielliptical spiracle in its ambulacral margin. Thus
there are 11 openings around the oral aperture, consisting
of ten spiracles and a separate anal opening. The ornamentation
of the deltoids and anal deltoids is the same
as in Nucleocrinus. There are two hydrospire folds on
each side of an ambulacrum, with a moderately long
hydrospire canal. On the inner surface of the hypodeltoid
is an inward-projecting hornlike process. Summit covered
by approximately 21 oral plates (Fig. 120).
Ambulacra five, linear, each 45 mm. long by 2 mm.
wide, recurved below, with lancet covered by side plates,
and 22 side plates in a space of 10 mm. along an ambulacrum.
Inner side plate present, with approximately four
cover-plate sockets to each side plate along the main food
groove. Side plates disposed as in Nudeocrinus, with
one large pore between adjacent side plates along the
deltoid and radial margins.
Occurrence.—Middle Devonian, Onondaga Formation,
Jeffersonville, Indiana.
Types.—Plesiotypes, 9,956, ten specimens, the largest
of which is described above, Gurley collection, Walker
Museum, University of Chicago.
ELAEACRINUS VENUSTUS (Miller & Gurley)
Plate 28, figures 1-6; text-figs. 122-125
Nucleocrintts venustus MILLER & GURLEY, 1894, p. 63, pl. 8, figs.
26-30.
Description.—The description is based on one of the
syntypes (1,317). Calyx calcitic, ellipsoidal in side view,
rounded pentagonal in top view, 16.5 mm. long by 12.5
mm. wide, with flat summit, concave constricted base,
and periphery near mid-height. Stem round, crenellar,
1.25 mm. in diameter, in sharp basal concavity. Basal
circlet lobed-pentagonal in aboral view, 2.75 mm. in
diameter, in sharp basal concavity, with three normally
disposed basals. Radials five, pentagonal in oblique basal
view, short, each 3.5 mm. long by 5 mm. wide, recurved
below, with short, narrow, flat sinus 2 mm. long by 1.5
mm. wide, and broad M-shaped radiodeltoid suture
formed at top of radial limbs. Deltoids overlap radials.
Deltoids four, long, bluntly lenticular, each 14 mm.
long by 6 mm. wide, each with a smooth central triangular
area with base equalling almost the full width of the
radiodeltoid suture, bordered on either side by a granulostriate
lenticular area, with two slitlike spiracles notched
in the adorai tip adjacent to the ambulacra. On the anal
side there are at least three, possibly four, anal deltoid
plates. A central smooth quadrangular hypodeltoid with
raised adorai end is bordered on either side by two
granulostriate cryptodeltoids that extend adorally beyond
the anal opening (one on each side) with one or two
small plates between them adorally from the anal opening
One of these plates, slightly below the other, is adjacent
to the anal opening and may represent a superdeltoid
plate. The adorai tips of the two cryptodeltoids abut
against three other oral plates on the anal side. Each
cryptodeltoid has one slitlike spiracle on the adorai tip
along the adjacent ambulacral margin. Thus there are
11 openings around the oral aperture, that is, ten spiracles
FIGURE PAGE
1-5. Troostricrinus reinwardti (TRoosT), holotype, 33,071
(now 139,105) (figs. 1-3), paratypes, 139,106 (figs. 4, 5),
Troost coll., U.S. Natl. Mus.; Middle Silurian, Niagaran,
Decatur County, Tennessee; 1, oral view ( X6); 2, "D"
ambulacral view (X3.4); 3, aboral view ( X6); 4, anal
view showing superdeltoid, cryptodeltoids and hypodeltoid
( X22); 5, polished section with "A" ambulacrum directed
upward, oral view ( X4.5) 106
6-8. Metablastus lineatus (SHumARD), neotypes, S4,958 (new
holotype, figs. 7,8); S4,957 (new paratype, fig. 6),
EXPLANATION OF PLATE 19
Springer coll., U.S. Natl. Mus.; Lower Mississippian, Upper
Burlington Limestone, Sagetown, III.; 6, aboral view
of "C" ambulacrum ( X10); 7, anal view of holotype
showing exposed cryptodeltoids where hypodeltoid is
missing (X6.6); 8, "CD" interambulacral view of holotype
(X2.2) 79
9. Metablastus varsouviensis (WORTHEN), syntype, 1,885,
A. H. Worthen coll., formerly Illinois State Mus., Springfield,
now Illinois Geol. Survey, Urbana; Mississippian,
Warsaw beds, Monroe County, Illinois; side view of one
of two imperfect types, in rock ( X7.1) 82