ECHINODERMATA - KU ScholarWorks - University of Kansas

48 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS
partly covered by a small hypodeltoid (pentagonal? ) on
the aboral side of the anal opening and that this plate is
one of the first to become detached. There are no hydrospire
slits on the anal side, so that eight hydrospire fields
are exposed.
Ambulacra six (normally five), each short, linear, 3.5
mm. long by 1 mm. wide, with lancet covered by side
plates and 45 side plates in 10 mm. length of an ambulacrum.
The primary side plates are subquadrangular, with
alate secondary side plates resting against the abmedialadoral
corners of the primary side plates. The surfaces
of the calyx plates are ornamented with fine growth striae
parallel to margins of plates.
Occurrence.—Middle Devonian, Traverse Group, Potter
Farm Formation, from shale pit just west of Evergreen
Cemetery, west of the city limits of Alpena, Michigan.
Types.—Plesiotypes, 30,736, four specimens, R. V.
Kesling collection, 1952, identified by REIMANN, University
of Michigan, Ann Arbor, Michigan.
TRIONOBLASTUS CANADENSIS (Billings)
Plate 4, figures 4-6; Plate 5, figures 7-9; text-figs. 60-63
Codaster canadensis BILLINGS, 1869, p. 79.
Description.—The description is based on characters
seen in the large hypotype of the Canadian Geological
Survey collection, supplemented by other specimens. Calyx
calcitic, obconical in side view, pentagonal in top view,
9.5 mm. long by 5 mm. wide, vault 2 mm. long, pelvis
7.5 mm. long, and pelvic angle of 30 degrees. The stem
is round, 1 mm. in diameter, smooth, with ill-defined outline
on basal circlet, which is conical, 4.5 mm. long by
3.5 mm. wide, with three normally disposed basals. Radials
five, each 5.5 mm. long by 3 mm. wide, with sinus
0.5 mm. long by 2 mm. wide; radials overlapping deltoids.
Deltoids four, arrow-shaped, confined to summit, each
1.5 mm. wide by 1.75 mm. long, with deltoid lips adjacent
to oral opening, deltoid crests low, and six exposed
hydrospire slits on each side of an ambulacrum extending
across adjacent radial limbs. On the anal side there are
three deltoid plates. The hexagonal epideltoid is adjacent
to the oral opening, and the horseshoe-shaped subdeltoid
rests on the aboral inner surface of the superdeltoid, with
limbs on either side of the anal opening. The subdeltoid
limbs are overlapped by the adjacent radial limbs. It is
assumed that a hypodeltoid plate was present on the
aboral side of the anal opening, because a small facet
occurs on the adorai face of the radial limbs for reception
of the hypodeltoid. Hydrospire slits absent in anal interradius,
and therefore there are eight exposed hydrospire
fields.
Ambulacra five, linear, each 3 mm. long by 0.5 mm.
wide, with lancet covered by side plates, and 43 side
plates in 10 mm. length of an ambulacrum. The lancet
stipe extends to within 0.5 mm. of the oral opening. The
side plates are normally disposed. The surfaces of the
calyx plates are ornamented with fine growth lines parallel
to plate margins.
Occurrence.—Middle Devonian, coral zone of Widder
beds, Hungry Hollow Formation, Thedford, Ontario.
Types.—Hypotypes, 3664, three specimens, the largest
used for illustration and description, same types used
by WHITEAVES (1887, 1889), p. 109, pl. 14, fig. 44a,
Geological Survey of Canada, Ottawa, Canada. Plesiotypes,
E21,098, 11 specimens, from tile yard at Thedford,
Charles Southworth collection; E11,760, two specimens,
Reimann collection, Buffalo Society of Natural Sciences,
Buffalo, New York.
TRIONOBLASTUS GRACILIS (Wachsmuth)
Plate 5, figures 1-3; text-figs. 64-66
Heteroschisma gracile WACHSMUTH, 1883, p. 354, text-figs. 1-2.
Description.—Calyx calcitic, subconical in side view,
pentagonal in oral view, base broken, 12.5 mm. long by
8 mm. wide, vault 2.5 mm. long, pelvis 10 mm. long,
pelvic angle 40 degrees, and periphery at radial lips well
above mid-height. The stem appears to be round, smooth,
with round central lumen, but too ill-defined to see
crenellae. Basal circlet conical in side view, rounded in
basal view, 4.5 mm. long by 4.5 mm. wide, with three
elongate normally disposed basais. Radials five, each 8
mm. long by 4 mm. wide, broadly quadrangular, with
narrow deep sinus 3 mm. long by 2 mm. wide, with radial
limbs projecting upward into coronal processes; radials
overlapping deltoids.
EXPLANATION OF PLATE 11
FIGURE PAGE
1-3. Hyperoblastus obesus (REimANN), holotype, E9,055, Buffalo
Soc. Nat. Sci.; Devonian, Ludlowville Formation (Demissa
beds), Smokes Creek, Windom, N.Y.; oral, "D"
ambulacral, aboral views (all X5.4) 33
4-6. Hyperoblastus eriensis (REimANN), paratype, E13,014,
Buffalo Soc. Nat. Sci.; Devonian, Tichenor Limestone,
Springbrook, N.Y.; oral, "D" ambulacral, aboral views
(all X8.1) 32
7-11. Hyperoblastus reimanni (KIER), holotype, 27,678 (figs
7-9); paratypes, 27,681 (fig. 10), 27,679 (fig. 11), Robert
R. Klinger coll., Univ. Michigan; Devonian, Silica Shale,
Unit 13, Medusa Portland Cement Company Quarry,
Silica, Lucas County, Ohio; 7-9, oral, "D" ambulacral,
aboral views (all X5.8); 10, "EA" interambulacral view
( X11); 11, "DE" interambulacral view ( X10.9) 35