316 PALEOZOIC PALEONTOLOGY. 
NUCLEOSPIRA VENTRICOSA Hall. 
Plate XXXVII., Fig. 16. 
See, also, p. 290, pl. XXX. 
In the shaley New Scotland beds a few specimens of this species, 
all of them internal casts, have been found. 
ANOPLOTHECA CONCAVA (Hall). 
Plate XXXVII., Figs. 11-15. 
See, also, p. 371. 
1859. Leptocelia concava Hall, Pal. N. Y., vol. III., p. 245, pl. 38, 
figs. 1-7. 
Description.—Shell small, subcircular or subelliptical in outline, 
varying from wider than long to longer than wide; cardinal angles 
rounded. Pedicle valve convex, subcarinate along the median line, 
sloping to the lateral and cardinal margins; beak small, slightly in- 
curved. Brachial valve flattened towards the lateral margins, with a 
broad, undefined, concave, mesial sinus, which is deeper in the middle 
of the valve than at the front margin. Surface of each valve marked 
by from fourteen to seventeen rather small, rounded plications, of 
which some of the central ones sometimes bifurcate; the median pli- 
cation of the pedicle valve is somewhat smaller than those on either 
side of it. 
The dimensions of an average specimen are: length, 5 mm.; width, 
5.5 mm. 
Remarks.—This little shell is one of the commonest species in the 
shaley member of the New Scotland beds, but it usually occurs in 
the form of moulds of the exterior and casts of the interior. 
