ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 89
with center at junction of interradial suture with the
radiodeltoid suture.
Ambulacra five, linear, with lancet exposed along the
median one-third of its width almost to the aboral end
of each ambulacrum. Side plates normally disposed, with
approximately five cover-plate sockets to each side plate
along main food groove, and two pores to each side
plate, one of which is almost even with a side plate
suture and the other about midway between the side
plate sutures. Surfaces of calyx plates ornamented by
fine granules arranged subparallel to plate margins along
growth lines.
Occurrence.—Lower Carboniferous, recorded as Devonshire
(may mean Derbyshire), England.
Type.—Plesiotype, 1,633, one specimen, James collection,
labelled Granatocrinus ellipticus, Walker Museum,
University of Chicago.
ORBITREMITES ELLIPTICUS (Sowerby)
Plate 43, figures 1-3, 10-11; text-figs. 186, 187
Pentremites elliptica SOWERBY, 1825, p. 317, pl. 11, fig. 4.
Elaeacrinus ellipticus SHUMARD, 1863, p. 112.
Description.—Calyx calcitic, fragmentary, 12.5 mm.
long by 12 mm. wide, ellipsoidal in side view, rounded
pentagonal in top view, with flat summit, and periphery
above mid-height. Stem and basais destroyed. Radials
five, elongate hexagonal in side view, reaching adorally
to periphery with narrow, shallow sinus 10 mm. long by
1.5 mm. wide. Deltoids overlap radials. The angle of
the radial limbs at the radiodeltoid suture, with center
at interradial suture is 85 degrees.
Deltoids four, large, broadly rhombic, reaching below
periphery, each 8 mm. long by 5.5 mm. wide, with one
large triangular spiracle in the middle of the depressed
adorai tip. On the anal side the triangular anispiracle is
located between a pentagonal superdeltoid and a pentagonal
hypodeltoid, with two hidden cryptodeltoids. Thus,
five openings ocur around the oral aperture, consisting of
four spiracles and an anispiracle. There is one hydrospire
fold on each side of an ambulacrum, terminating
admedially in a hydrospire plate.
Ambulacra five, linear, raised, each 16 mm. long by
1.5 mm. wide, with lancet exposed along the middle onethird
of its width almost to the aboral end, and 26 side
plates in a space of 10 mm. along an ambulacrum. There
are two pores to each side plate along the deltoid and
radial margins. The surfaces of the calyx plates are almost
smooth, with fine growth striae subparallel to plate
margins, and granular raised ridges immediately aboral
to each spiracle and anispiracle.
Occurrence.—Lower Carboniferous, upper part of
Clitheroe Limestone (C 2) of Salt Hill Knoll, Clitheroe,
Lancashire, England (Beaver collection), and Carboniferous
limestone, Yorkshire, England (deKoninck collection).
Types.—Plesiotypes, 245, 11 specimens, deKoninck
collection, old numbers, 2,324 and 467, Harvard Museum
of Comparative Zoology, Cambridge, Mass.; one unnumbered
specimen, Beaver collection, sent by DR. JOYSEY from
Cambridge, England, Humble Oil & Refining Co., Houston,
Texas. The above description is based on the specimen
in the Beaver collection.
Genus PENTREMITES Say, 1820
Type-species, by subsequent designation (ETHERIDGE & CARPENTER,
1886).—encrina Godonii DEFRANCE, 1819.
Generic diagnosis.—Spiraculate blastoids with five
spiracles or four spiracles and an anispiracle, with the
anispiracle excavated in one anal deltoid plate, ?two,
three to seven or more hydrospire folds on each side
of an ambulacrum, oral and anal areas covered by
many imbricate plates, one pore between side plates
along deltoid and radial margins, lancet almost completely
exposed, ambulacra petaloid, radials overlap
deltoids, and shape of calyx in side view rounded obconical
or club-shaped. Mississippian -Pennsylvanian,
Alabama, Tennessee, Kentucky, Indiana, Illinois, Missouri,
Iowa, Oklahoma, Arkansas, Mississippi, Montana,
Alberta, ?Alaska.
Remarks.—The genus Pentremites was probably
derived from Devon oblastus by fusion of the anal
deltoid plates into one, and continued downward
migration of the deltoid plates, and outward migration
of the lancet plates. A detailed description of the
neotype (new holotype) of P. godoni is reserved for
another paper to appear in the Journal of Paleontology.
EXPLANATION
FIGURE
PAGE
1-6. Elaeacrinus venustus (MILLER & GURLEY). 1 3. Syntype,
6,114, Univ. Chicago; Devonian, Columbus, Ohio;
oral, "D" ambulacral, aboral views of figured type (Miller
& Gurley, 1894, pl. 8, fig. 26-30) (all X4.1).-4-6.
Syntype, 1,317, Univ. Cincinnati; Devonian, Columbus,
OF PLATE 28
Ohio; oral, "D" ambulacral, aboral views (all X3.7) 69
7-10. Elaeacrinus verneudi ROEMER, plesiotype, 9,956, Gurley
coll., Univ. Chicago; Devonian, Jeffersonville Limestone,
Jeffersonville, Ind., 7-9, oral, aboral, "D" ambulacral views
( X1.7); 10, enlarged oral view of summit ( X4.3) 68