ECHINODERMATA - KU ScholarWorks - University of Kansas

BLASTOID STUDIES 97
Occurrence.—Middle Devonian, Ludlowville Formation
(Tichenor Limestone), Cazenovia Creek, Springbrook,
New York.
Type.—Holotype, E11,811, one specimen, Fred Wattles
collection, Buffalo Society of Natural Sciences, Buffalo,
New York.
PLACOBLASTUS LUCINA (Hall)
Plate 32, figures 4-7, 10; text-figs. 200, 201
Nucleoc-rinus lucina HALL, 1862, p. 148, pl. 1, fig. 16.
Elaeacrinus lucina SHUMARD, 1866, p. 369.
Olivanites lucina HAMBACH, 1903, p. 50.
Description.—Calyx calcitic, flattened spherical in side
view, pentagonal in top view with moderately sharp
ambulacra and concave interambulacra, 9 mm. long by
9 mm. wide, with slightly concave base. Stem round, 0.25
mm. wide, in flat basal circlet, crenellar, with small round
lumen. Basal circlet rounded pentagonal in aboral view,
2.5 mm. in diameter, almost flat to slightly concave, with
three normally disposed basals. Radials five, short, wide,
pentagonal in side view, each 3 mm. long by 4 mm. wide,
with short, shallow sinus 1.5 mm. long by 1 mm. wide,
recurved below in slightly concave aboral surface. Deltoids
overlap radials.
Deltoids four, sublenticular, each 8 mm. long by 5
mm. wide, with two hemielliptical spiracles in the adorai
tip along ambulacral margins. In top view the deltoids
are slightly concave inward, the aboral end of each abutting
against a large arrow-shaped oral plate. On the anal
side at least three anal deltoids occur, the two lenticular
exposed cryptodeltoids along ambulacral margins, with
the elongate subquadrangular hypodeltoid between. On
the adoral side of the anal opening there are two polygonal
plates between the adorai tips of the cryptodeltoids.
The plate adjacent to the anal opening is here interpreted
to be a superdeltoid plate, and the adorally disposed
plate is interpreted to be an accessory anal oral
plate. Calyx plates ornamented as in Nucleocrinus. There
are two semielliptical slitlike spiracles on either side of
the anal opening, one each in the adorai tip of each cryptodeltoid.
Thus, 11 openings surround the oral aperture,
consisting of ten spiracles and the separate anal opening.
There are two hydrospire folds on each side of an ambulacrum,
with a moderately long hydrospire canal.
Ambulacra five, linear, recurved below, each 11 mm.
long by 1 mm. wide, with lancet covered by side plates,
and 40 side plates in a space of 10 mm. along an ambulacrum.
Side plates normally disposed, with an inner side
plate, as in Nucleocrinus.
Occurrence.—Middle Devonian, Hamilton beds, Most
cow, New York.
Types.—The holotype is on deposit at the American
Museum of Natural History, Hall collection, 5038/2, and
is slightly damaged, but usable for general identification of
other specimens. Topotypes, 13,276, Hall collection, one
specimen; 19,049, two specimens, one of which is Nucleocrinus
elegans, Gurley collection, Walker Museum, University
of Chicago. The above description is based on
specimen 19,049.
Genus POROBLASTUS Fay, n. gen.
Type-species, by original designation (herein).—PentretnItes ( Granatocrinus?)
granulosus MEEK & WORTHEN, 1865.
Generic diagnosis.—Spiraculate blastoids with nine
spiracles, or eight spiracles and anispiracle, the anispiracle
located between an epideltoid and hypodeltoid,
radials overlapping deltoids, hydrospire plate
present, one pore between side plates along deltoid
margins but two pores to each side plate along radial
margins, one hydrospire fold on each side of an
ambulacrum, lancet covered at aboral end but gradually
exposed to one-third of its width near the adoral
end, base concave, and shape ellipsoidal. Mississippian,
Illinois, Iowa, Missouri.
Remarks.—The genus Poroblastus may have been
derived from Lophoblastus by infolding of radial mar-
FIGURE
EXPLANATION OF PLATE 32
PAGE
1-3. Placoblastus eriensis (REImANN), holotype, El 1,811, Fred
Wattles coll., Buffalo Soc. Nat. Sci.; Middle Devonian, 8.
Tichenor Limestone, Cazenovia Creek, Springbrook, N.Y.;
oral, "D" ambulacral, aboral views of specimen described
as Nucleocrinus verneuili eriensis (all X2.4) 97
4-7,10. Placoblastus lucina (HALL), ?topotypes, 19,049 (figs
4-6,10), Gurley coll., Univ. Chicago, Devonian, Hamilton
Group, Moscow, N.Y., and 13,276 (fig. 7), James Hall 9.
coll., Univ. Chicago, Middle Devonian, New York; 4-6,
one of two specimens labelled Nucleocrinus elegans, oral,
"D" ambulacral, aboral views ( X5.1); 10, specimen illustrated
in fig. 4, showing large plate between adorai tips
of cryptodeltoids ( X3.6); 7. Aboral view of polished
cross section showing hydrospire folds of "E" ambulacrum
( X12.6) 97
Placoblastus angularis (LYON), plesiotype, E9,057, Reimann
coll., Buffalo Soc. Nat. Sci. (one of five specimens
labelled Nucleocrinus powelli; Middle Devonian, Ludlowville
Formation (Tichenor Limestone), Cazenovia Creek,
Springbrook, N.Y.; aboral view of polished cross section
of "E" ambulacrum showing hydrospire folds ( X 9.3) 95
Nucleocrinus meloniformis (BARRIs), plcsiotype, E21,120,
Charles Southworth coll., Buffalo Soc. Nat. Sci.; Middle
Devonian, Hungry Hollow Formation (coral zone of
Widder beds), tile yard, Thedford, Ontario, polished section
of "E" ambulacrum showing two folds on right originating
at deltoid ( X19) 86