LOWER HELDERBERG ROCKS 
Trematospira globosa (n. s.). 
Plate XXXYI. Fig. 1 a - p. 
Waldheimia globosa : Descr.of New Species of Pal. Fossils, in Regents’Report for 1856, p.47. 
Shell subglobose or ovoid. Ventral valve a little larger and slightly less 
gibbous than the opposite one, most gibbous in the umbonial region : 
beak prominent, rounded and arched, perforate at the extremity by a 
round aperture, the lower side of which is formed by a deltidium. 
Dorsal valve shorter than the ventral, very gibbous in the middle : 
beak incurved. 
Surface marked by twelve to sixteen somewhat angular plications on 
each valve, two or three of which are slightly depressed on the middle 
so as to produce, sometimes, a faint emargination in front; the de¬ 
pressed plications smaller than the others, and often becoming obso¬ 
lete before reaching the beak. A few strong concentric imbricating 
lines of growth cross the plications : shell granulose. 
The globose form and elevated subangular plications of this shell, as well as the 
generally more distinctly imbricating lamelke, giving it a rude form, will serve to 
distinguish it from the following species of the same rock. 
Fig. 1 a - c. Dorsal, profile, and front views of young individuals. 
Fig. 1 f - k. Individuals of larger size. 
Fig. 1 l — p. Individuals of full size, showing some differences in the plications, and in the 
elevation of the beak. 
Geological position and locality. In the shaly limestone of the Lower Helderberg 
group : Helderberg mountains, Albany county. 
TreiMatospira formosa (n. s.). 
Plate XXXYI. Fig. 2 a - t. 
Waldheimia formosa : Descr. of New Species of Pal. Fossils in Regents’ Report for 1856, p.48. 
Shell longitudinally ovate. Ventral valve tapering towards the beak : 
beak prominent, rounded, arched or incurved, truncated at the apex 
by a round perforation, one side of which is formed by the deltidium. 
Dorsal valve gibbous, sometimes most prominent near the umbo : beak 
closely incurved beneath the opposite one. 
