ECHINODERMATA - KU ScholarWorks - University of Kansas

adorai ends of the cryptodeltoids. The adorally disposed
plate is termed an accessory anal oral plate and the aborally
disposed plate a superdeltoid. The accessory anal
oral may override the superdeltoid, thus giving the appearance
of one plate in this position. Hydrospire folds
two on each side of an ambulacrum, with elongate hydrospire
canals.
Ambulacra five, linear, recurved below, each 22 mm.
long by 1 mm. wide, with lancet covered by side plates,
and 34 side plates in a space of 10 mm. along an ambulacrum.
Inner side plate present. Side plates arranged as
in Nucleocrinus. The ambulacra are covered by a large
set of cover plates along the spiracles. The adorai tips of
the deltoids are pierced by two slitlike spiracles along the
ambulacra, and the cryptodeltoids each have one spiracle
in its adorai tip, separate from the anal opening. Thus, 11
openings surround the oral aperture, consisting of ten
spiracles and a separate anal opening. Ornamentation of
calyx plates similar to that of Nucleocrinus.
Occurrence.—Middle Devonian, Ludlowville Formation
(Tichenor Limestone), Cazenovia Creek, Springbrook,
New York (described specimen from here). Hamilton
Group, Charlestown, Indiana (13,890). Jeffersonville
Limestone, Falls of the Ohio, Louisville, Kentucky
(19,052).
Types.—Plesiotypes, E9,057, five fragmentary paratypes
of Nucleocrinus powelli, Reimann collection (1935),
Tichenor Limestone; E9,058, two paratypes of Nucleocrinus
powelli one of which was used for above description,
Reimann collection (1935), Tichenor Limestone;
E 11,629, one paratype of Nucleocrinus powelli, Wattles
collection (1940), Tichenor Limestone, Buffalo Society of
Natural Sciences, Buffalo, New York. Plesiotypes, 13,890,
36 silicified specimens; 19,052, one specimen, Gurley collection,
Walker Museum, University of Chicago.
BLASTOID STUDIES 95
FIGURES 198-201. Species of Placoblastus FAY, n. gen.,
Middle Devonian, New York. 198, 199. P. angularis
(LYoN), Ludlowville Formation, Springbrook, N.Y.
(Buffalo Soc. Nat. Sci., nos. E9,057, E11,629); 198, part
of "B" ambulacrum, showing main, inner, and outer side
plates (no. E11,629), X15; 199, cross section of "E" ambulacrum,
aboral view (no. E9,057), X15. 200, 201.
P. lucina (HALL), Hamilton Group, Moscow, N. Y.
(Univ. Chicago, nos. 13,276, 19,049); 200, partial cross
section of "E" ambulacrum, aboral view (no. 13,276),
X15; 201, summit and anal areas (no. 19,049), X15. [Explanation.—An,
anal opening; Bf, brachiolar facet; Bp,
brachiolar pit; "C," amb.; CR, cryptodeltoid; "D," amb.;
D, deltoid; HD, hypodeltoid; ISp, inner side plate; L,
lancet; 0, oral plate; OSp, outer side plate; P, pore; S,
spiracle; Sp, main side plate; Su, superdeltoid.]
HD