133 
PALAEONTOLOGY OF NEW-YORK. 
edges. On the concave side at the base are two large and strongly arching- 
plates, which extend in long angular points to the lower angles of the 
concave side; the angles being occupied by a bent carinate plate, of 
which the lower narrow extremity reaches to the base of the body. 
On the convex side the base is longer, and formed of three distinct 
plates, the central one of which is hexagonal and the others apparently 
pentagonal. On the concave side, the basal plates are succeeded by a 
large irregular central plate, and this one by a range of smaller plates; 
while the angles present each three plates in direct succession. The 
convex side above the base shows, somewhat irregularly, five ranges of 
small jdates. The summit is broken off. 
A specimen from the limestone has two round spine-like processes, 
one from each side of the summit, which, under a lens, appear not to 
be jointed; and from the centre is a projection which may be a short 
proboscis, or the ovarian plates protruded from pressure. These parts, 
however, are too obscure to be characteristic ; and so far as regards 
* 
generic relations and differences, we must rely upon the fundamental 
structure of the body, from the irregularity of which I propose to de¬ 
signate this fossil. 
CJemis Anomalocystites (n. g.). 
[ Gr. ctvwfuaXi^, irregularis ; xuaVo?, vesica .] 
Body semielliptical or semiovoid : sides unequal; the vertical outline 
oval or ovoid, plano-convex or concavo-convex; the transverse outline 
semielliptical, the base of which is straight or more or less concave : 
the two sides composed of an unequal number of plates. Basal plates 
three on the convex side, two on the concave side : second series, two 
large plates at the angles, and four (or five?) on the convex side ; third 
series, four on the convex side, one at each angle, and a large plate on 
the concave side; a fourth, fifth, and sixth series of plates on the 
convex side, and a fourth series on the concave side. Base oblique, with 
the convex side longer, and a deep concavity for the insertion of the 
column. Pectinated rhombs apparently none. 
