370 PALEOZOIC PALEONTOLOGY. 
somewhat the appearance of interrupted radiating coste, and which 
are really the bases of parallel, concentric rows of spines. 
The dimensions of a nearly-perfect specimen from the Hamilton 
shale of New York are: length, 22 mm.; width, 25 mm.; thick- 
ness, 15 mm. 
Remarks.—This species is rarely represented in the Onondaga lime- 
stone of New Jersey, the only specimens observed being imperfect im- 
pressions of the exterior. These impressions, however, retain the 
characteristic surface markings of the species, and indicate a shell 
which was in no essential particulars different from the Onondaga 
and Hamilton representatives of the species in New York. The 
above description has been drawn up from New York specimens in 
the absence of satisfactory material in the New Jersey collections. 
ANOPLOTHECA ACUTIPLICATA (Con.). 
Plate LI., Figs. 14-17. 
See, also, pp. 377 and 383. 
1867. Leptocela acutiplicata Hall, Pal. N. Y., vol. VI., p. 365, pl. 
57, figs. 30-39. 
/ oO 
Description.—Shell plano-convex, subcircular or subovate in: out- 
line. Pedicle valve moderately convex, its greatest elevation near the 
centre; beak acute, incurved so that it points at about right angles 
to the plane of the valve and projects slightly beyond the brachial 
valve; marked by about nine strong, angular, simple, radiating pli- 
cations, the central one being somewhat depressed toward the front 
and bordered on each side by a larger one. Brachial valve flat or 
slightly convex, a little depressed medially, its plications similar to 
those of the opposite valve. Surface of both valves marked by a 
few rather strong, subimbricating lines of growth toward the margin. 
The dimensions of a nearly-perfect specimen are: length, 12 mm. ; 
width, 13 mm.; thickness, 4 mm. 
Remarks.—TVhis species is hardly distinguishable from A. flabel- 
lites of the Oriskany fauna. It does not grow as large as the usual 
representatives of the Oriskany shell, but it is doubtful whether the 
two species should be considered as distinct. 
