ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 31
mm. long by 5.5 mm. wide, pentagonal in basal view,
composed of three normally disposed basais. Radials five,
each 11.5 mm. long by 4.5 mm. wide, with deep, narrow,
tapering sinus 10.5 mm. long by 2.5 mm. wide; radials
overlapping deltoids.
Deltoids four, short, not visible in side view, triangular,
covered by radial limbs, with deep median
septum between adjacent hydrospire canals. On the anal
side, the quadrangular hypodeltoid (missing) abuts
against the radial limbs and rests on two internal cryptodeltoids.
The cryptodeltoids are on either side of the
anal opening, are overlapped by the radial limbs, and
overlap the superdeltoid internally on the adorai side of
the anal opening. They appear to be continuous with
the two anal septa of the superdeltoid and separate the
anal opening from the adjacent hydrospire canals internally.
The superdeltoid, adjacent to the oral opening,
is homologous with the deltoid lips of the other four deltoids
and together with them helps to surround the oral
opening. Spiracles five, with four piercing the adorai
ends of the four deltoids and the anispiracle formed between
the superdeltoid and hypodeltoid. Five hydrospire
folds occur on each side of an ambulacrum, making ten
fields in all, with aboral ends of the outermost slits exposed.
Ambulacra five, linear, each 13 mm. long by 2 mm.
wide, slightly recurved onto aboral side, lancet covered
by side plates, with 22 side plates in 10 mm. The side
plates are normally disposed, with a subtriangular secondary
side plate on the adoral-abmedial bevelled corner
of each primary side plate, and a large bifasiculate
brachiolar muscle scar split between the primary and
secondary side plates. The pores are formed as gaps between
side plates and margins of the radial sinuses. The
brachiolar pit is admedial from the brachiolar facet, leading
adorally to a side food groove. Two side cover-plate
sockets occur on each side food groove and four main
cover-plate sockets on each side plate along the main food
groove. A curved pore furrow occurs on each primary
side plate, curved aborally and abmedially around the
brachiolar facet, ending in a pore. Near the radiodeltoid
suture the side plates are firmly fixed against the radial
sinus and pores are absent. The surfaces of the calyx
plates are ornamented with fine growth lines parallel
to plate margins.
Remarks.—This species was selected as the type-species
because it clearly shows the internal and external features
that characterize the genus.
Occurrence.—Middle Devonian, coral zone of the
Widder beds, Hungry Hollow Formation, Joseph Bell
Quarry, Thedford area, Ontario, Canada.
Type.—Holotype, E15,934, one specimen, collected
by CHARLES SOUTHWORTH (1943), purchased by Buffalo
Society of Natural Sciences, Buffalo, New York.
HYPEROBLASTUS BASSLERI (Reimann)
Plate 52, figures 3-5
Pentremitidea bass/eni REIMANN, 1945, p. 33, pl. 7, figs. 3-5.
Description.—The figured specimen is 27 mm. long
by 13 mm. wide, vault 17 mm. long, pelvis 10 mm. long,
and pelvic angle 55 degrees.
Occurrence.—Middle Devonian, Traverse Group,
Thunder Bay Formation (now Partridge Point Formation),
Partridge Point, near Alpena, Michigan.
Type.—Paratype, E15,337, one specimen, Buffalo
Society of Natural Sciences, Buffalo, New York.
HYPEROBLASTUS CUMMINGSI (Reimann)
Plate 9, figures 1-3
Pentremitidea cummingsi REIMANN, 1935, p. 28, pl. 2, fig. 19, pl.
4, fig. 8.
Description.—The figured specimen is 14 mm. long
by 9.5 mm. wide, vault 11.5 mm. long, pelvis 2.5 mm.
long, and pelvic angle on basal circlet 75 degrees and on
radial bodies 160 degrees. Approximately five hydrospire
folds occur on each side of an ambulacrum.
Occurrence.—Middle Devonian, coral zone of Widder
beds, Hungry Hollow Formation, Arkona, Ontario,
Canada.
Type.—Hypotype, E15,935, one specimen, Buffalo
Society of Natural Sciences, Buffalo, New York.
HYPEROBLASTUS DOTIS (Reimann)
Plate 9, figures 7, 9-11; text-fig. 28
Pentretnitaea dotis REIMANN, 1945, p. 37, pl. 6, fig. 13.
Description.—The figured specimen is 9 mm. long
by 5.5 mm. wide, vault 5.5 mm. long, pelvis 3.5 mm.
long, and pelvic angle 60 degrees on basal circlet and 130
degrees on radial bodies. Five hydrospire folds occur on
each side of an ambulacrum.
Occurrence.—Middle Devonian, coral zone of Widder
beds, Hungry Hollow Formation, Thedford, Ontario.
Types.—Holotype, E15,401, one specimen; paratypes,
E13,052, four specimens, Buffalo Society of Natural Sciences,
collected by CHARLES SOUTHWORTH (1941), identified
by REIMANN ( 1944); an ambulacrum of one of these
specimens is shown in text-figure 23.
HYPEROBLASTUS ERIENSIS (Reimann)
Plate 11, figures 4-6
Pentremitidea eriensis REIMANN, 1945, pp. 37-38, pl. 7, fig. 11.
Description.—The figured specimen is 7.5 mm. long
by 5.5 mm. wide, vault 6 mm. long, pelvis 1.5 mm. long,
and pelvic angle 75 degrees on basal circlet and 160
degrees on radial bodies. Base fiat, triangular.
Occurrence.—Middle Devonian, Tichenor Limestone,
Springbrook Station, New York.