ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 39
calyx about 10 mm. in diameter. The prominent feature
that distinguishes this species from all others is the elongate
winglike extensions of the radial limbs outward from
the calyx.
Occurrence.—Lower Mississippian, Burlington Limestone,
Burlington, Iowa.
Type.—Holotype, 379, Harvard Museum of Comparative
Zoology, Cambridge, Mass.
OROPHOCRINUS VERUS (Cumberland)
Plate 16, figures 7-9
Mitra vera CUMBERLAND, 1826, p. 31, pl. B, figs. 1-2.
Description.—Calyx calcitic, club-shaped in side view,
15 mm. long by 13 mm. wide, pelvis longer than vault.
This species is distinguished from all others by its short,
wide calyx and pelvis slightly longer than the vault. It
is similar to Orophocrinus puzos, which has a shorter
pelvis and longer vault.
Occurrence.—Lower Carboniferous, Mountain Limestone,
Lancashire, England.
Type.—Plesiotype, S3,237, one specimen, Springer
collection, U. S. National Museum, Washington.
Genus PENTREMITIDEA d'Orbigny, 1849
Type-species, by original designation.—Pentrernites pailletti VER-
NEUIL, 1844.
Generic diagnosis.—Fissiculate blastoids with eight
hidden hydrospire fields that open into spiracular
slits, approximately eight hydrospire slits in each field,
with a superdeltoid, subdeltoid, and hypodeltoid on
the anal side, hydrospire absent on the anal side, lancet
covered by side plates, with possible inner side plate
present; calyx steeply conical in side view, with narrow
deep sinuses. Devonian, Spain.
Remarks.—The genus Pentremitidea was probably
derived from a form like Deltoschisma, the subdeltoid
being formed by fusion of the two cryptodeltoids,
the sinuses closing to form spiracular slits,
and the anal hydrospire fields becoming atrophied.
PENTREMITIDEA PAILLETTI (de Verneuil)
Plate 2, figures 1-11; text-figs. 42-45
Pentremrtes pailletti VERNEUIL, 184413, p. 216; 1844a, p. 213, pl. 2,
figs. 4 - 5.
Description.—Calyx calcitic, conical in side view, pentalobate
in top view, 16 mm. long by 9.5 mm. wide, with
vault 2 mm. long, pelvis 14 mm. long, and pelvic angle
on basals 25 degrees and on radial bodies 40 degrees,
with periphery at radial lips. Stem round, small, crenellar,
broken in described specimen but present in another
one. Basal circlet conical in side view, rounded pentagonal
in basal view, 8 mm. long by 7 mm. wide, gradually
tapering aborally. Radials five, constricted, broadly
pentagonal in side view, lobed in top view, each 9 mm.
long by 3.75 mm. wide, with short, narrow, steep-sided
sinus 3 mm. long by 2.5 mm. wide. Radial limbs shorter
on the anal side than on the other four sides; radials overlapping
deltoids.
Deltoids four, short, not visible in side view, each
1.75 mm. long by 1 mm. wide, lancet-shaped, with open
spiracular slits along ambulacral margins, deep septa,
and prominent V-shaped deltoid lips. Approximately
eight hidden hydrospire slits are present on each side of
each deltoid except in the anal area, where hydrospires
are lacking. These slits extend to the radial limbs approximately
at right angles to the radiodeltoid sutures,
opening into each spiracular slit along the ambulacral
margins. On the anal side three anal deltoids occur, an
elongate V-shaped superdeltoid, upon which a U-shaped
subdeltoid rests aborally on the adorai end of the anal
opening, and a pentagonal hypodeltoid (missing, but
facets present) that covers the subdeltoid limbs and abuts
against the adjacent radial limbs.
Ambulacra five, short, moderately wide, each 4.5 mm.
long by 1.75 mm. wide, with lancet covered by side plates,
18 side plates to each ambulacrum, and 45 side plates in
10 mm. length of an ambulacrum, if extended. Each primary
side plate is elongate abmedially-admedially, quadrangular,
with a subtriangular secondary side plate on
the admedial-adoral bevelled corner. There appears to
be a small triangular inner side plate adjacent to the
main food groove, between primary side plates, with
apex of triangle at suture between adjacent side plates.
Approximately four main cover-plate sockets correspond
to each side plate along the main food groove, and four
or five side cover-plate sockets along each side food
groove. The surfaces of the calyx plates are ornamented
with fine growth lines parallel to plate margins.
Remarks.—The many species referred to Pentremitidea
do not fit in this genus and must be reclassified in
other genera, such as Hyperoblastus, Cordyloblastus, and
Deltoschisma. Except for Hyperoblastus, it is common to
find species of these genera mixed in the same lot of
specimens in a museum. Hyperoblastus occurs in North
America, and the others in Europe.
Occurrence.—Devonian, Calizas de Ferrofies, Asturias;
Calizas de Arnao, near Sabero (Leon), Spain.
Types.—Topotypes, 297, 11 specimens (large one used
for description), Schultze collection, old no. 2352, with
specimens of other genera, Sabero, Harvard Museum of
Comparative Zoology, Cambridge, Mass.; 547, seven specimens,
de Koninck collection, old no. 2353, Asturias, Harvard
Museum; S3,622, three specimens, S3,62I, one specimen,
Springer collection, Sabero, U.S. National Museum,
Washington; 13,876, six specimens, one of which belongs
to Deltoschisma, Gurley collection, Asturias, Walker
Museum, University of Chicago.