ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 73
Ambulacra five, linear, recurved below, each 11 mm.
long by 1 mm. wide, with median one-third of width
of lancet exposed and 25 side plates in 10 mm. length of
an ambulacrum. The side plates are normally disposed,
with approximately two pores to each side plate, a hydrospire
plate present, and five or six main cover-plate
sockets to each side plate along the main food groove.
The surfaces of the calyx plates are ornamented by fine
granules that are arranged along growth lines.
Occurrence.—Lower Carboniferous Limestone, Lancashire
and Yorkshire, England.
Types.—Plesiotype, 13,877, one specimen, Gurley collection,
Walker Museum, University of Chicago. Plesiotype,
241, one specimen, deKoninck collection, old no.
2,330, Carboniferous Limestone, Settle, Yorkshire, England,
Harvard Museum of Comparative Zoology, Cambridge,
Mass.
Genus GLOBOBLASTUS Hambach, 1903
Type-species, by original designation (monotypy), and by subsequent
designation (Bassler, 1938).—Pentremites norwoodi
OWEN & SHUMARD, 1850.
Generic diagnosis (emend. FAY, 1960).—Spiraculate
blastoids with five spiracles, composed of four
spiracles and an anispiracle, with superdeltoid, two
cryptodeltoids, and a hypodeltoid on the anal side;
lancet covered by side plates except near adorai end,
radials overlapping deltoids, approximately two pores
to each side plate along radial margins, hydrospire plate
present, deltoids short; two hydrospire folds on each
side of an ambulacrum; calyx subglobular in shape.
Mississippian, Illinois, Iowa, Missouri.
Remarks.—The genus Globoblastus was probably
derived from a form similar to Devonoblastus in
which a hydrospire plate and infolded pores formed
along the ambulacra, the hydrospires becoming reduced
in number, and form of the calyx subglobular.
GLOBOBLASTUS NORWOODI (Owen & Shumard)
Plate 44, figures 1-7; text-figs. 139-142
Pentremites norwoodi OWEN & SHUMARD, 1850, p. 64, pl. 7, figs.
13a-c.
Description.—The new holotype (neotype) is ellipsoidal,
15 mm. long by 12 mm. wide, with concave base.
Stem round, approximately 1 mm. in diameter, with about
40 crenellae extending toward center. Basal circlet small,
in deep concavity, with three normally disposed basais.
Radials each 15 mm. long by 7 mm. wide, recurved in
basal concavity, with long narrow sinuses; radials overlapping
deltoids.
Deltoids four, short, each 2 mm. long by 2 mm. wide,
with a single spiracle at their adorai tips. On the anal
side the superdeltoid is 1 mm. long by 2 mm. wide, and
hypodeltoid 1 mm. long by 2 mm. wide, with anispiracle
between. The two cryptodeltoids are covered over by the
hypodeltoid, are infolded internally into hydrospires, and
are overlapped by the radial limbs. Adorally the cryptodeltoids
separate the anal opening from the adjacent hydrospire
canals internally, and rest on the aboral surface
of the superdeltoid. There are two hydrospire folds on
each side of an ambulacrum, with a hydrospire plate
present; approximately two pores to each side plate are
excavated in the ambulacral margins of the radial plates.
The oral opening is surrounded by the four deltoid lips
and the superdeltoid, and by five spiracles, or four spiracles
and an anispiracle.
Ambulacra five, linear, each 16 mm. long by 1.5 mm.
wide, recurved below, with lancet covered by side plates
along the aboral one-half of each ambulacrum but exposed
one-third of its width near the oral opening. There
are 30 side plates in a space of 10 mm. along an ambulacrum,
with approximately two pores to each side plate
(one aligned with side plate suture and one aligned
approximately near middle of the ambulacral margin
of each side plate), with secondary side plate normally
disposed. There are four cover-plate sockets to each side
plate along the main food groove and two or three side
cover-plate sockets along each side of a side food groove.
The interradial sutures are depressed and the surfaces of
the calyx plates are ornamented with finely granular
growth lines parallel to plate margins.
Remarks.—The original types were probably destroyed
in the fire at Indiana University in 1883 and
therefore neotypes are here selected.
Occurrence.—Lower Mississippian, upper part of Burlington
Limestone, Burlington, Iowa.
Types.—Neotypes, S4,956 (new holotype), S4,955
(new paratype), Springer collection, old no. S3,759, part
of 31 specimens, U. S. National Museum, Washington.
EXPLANATION OF PLATE 22
FIGURE
PAGE
1-3. Cordyloblastus roemeri (ETHERIDGE & CARPENTER), plesiotype,
S3,615, Springer coll., U.S. Natl. Mus.; Lower Devonian,
Calizas de Arnao, Le6n, Spain; oral, "D" ambulacral,
aboral views (all X8.2).
4-9. Cordy/oHastus /usitanicus (ETHERIDGE & CARPENTER).
4 6. Plesiotype, S3,6I6, Springer coll., U.S. Natl.
Mus.; Middle Devonian, Gerolstein, Eifel, Germany; oral,
"D" ambulacral, aboral views (all X9.8). 7 9.
Plesiotype, 19,091, Gurley coll., Univ. Chicago; Middle
Devonian, Gerolstein, Germany; oral, aboral, "D"
ambulacral views (all X 11.5) 57