LOWER HELDERBERG ROCKS. 
Trematospira multistriata (n. s.). 
Plate XXIY. Fig. 3 a-t; and Plate XXYIIT A. Fig. 5 a - f. 
Spirifer multistnatus : IIall, Descr. New Species Pal. Fossils, in Regent’s Report, etc. 1856. 
Shell transversely oval or subrhomboidal, with angles rounded : hinge 
line slightly declining on each side of the centre ; cardinal extremities 
rounded. Ventral valve moderately convex towards the beak, with a 
broad not sharply defined sinus below, which often becomes obsolete 
before reaching the beak : beak perforate, abruptly incurved over the 
opposite. Dorsal valve the more convex, the middle elevated in a broad 
scarcely defined lobe : beal,c closely incurved beneath the other, filling 
the foramen in the ventral valve. Area narrow, strongly striated lon¬ 
gitudinally. 
Surface granulose or punctate, and marked by numerous fine striae which 
bifurcate once or oftener between the beak and base of the shell, 
crossed concentrically by imbricating lamellae of growth. 
This species was originally described as a Spirifer , from having the appearance 
of an area, and which is sometimes enhanced by the partial displacement of the 
valves. A separate valve, fig. 3 u, shows obscurely some characters of the ventral 
valve of Spirifer. The junction of the valves and absence of a true area, as well as 
the insertion of the beak of the dorsal valve beneath the opposite, are well shown 
in several of the figures. 
Fig. 3 a-t. Illustrations stowing gradation of size, variety of form, etc. 
Fig. 3 y. Enlargement of the striae. 
PLATE XXVIII A. 
Fig. 5 a. An individual of medium size, having the beaks closely incurved, and without 
indication of an area. 
Fig. 5 b. Dorsal view, where the minute perforation in the beak of the ventral valve is bare¬ 
ly seen above the summit of the opposite one. 
Fig. 5 c, cl, e. Ventral, front, and profile views of the same individual. 
Fig. 5 f. The interior of a ventral valve, showing the remains of internal spires. 
Geological position and locality. In the shaly limestone of the Lower Helderberg 
group : Helderberg mountains, Schoharie, etc. 
[ Palaeontology III.] 
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