98 PALEONTOLOGY OF NEW-YoRK. 
136. 10. LINGULA OBTUSA (n. sp.). 
Pu. XXX. Figs. 7 a,b, c. 
Broad-ovate, obtuse at the apex and regularly rounded below, depressed in front, but 
very prominently convex on the umbones ; beaks obtuse, prominent, not terminal ; margin 
of the shell a little produced beyond the beaks ; surface apparently smooth, but, under a 
magnifier, exhibiting fine concentric and radiating striz. 
This shell is easily distinguished by its ovate form, with very obtuse apex ; the beak is 
prominent and elevated, with a narrow space between it and the margin of the shell. The 
outline from beak to base is much more arched than in any other species. 
Fig. 7 a. A very perfect specimen of large size, giving the exact form of the shell : radiating strie 
scarcely visible. 
Fig. 7 6. Another specimen, the form not quite as perfect as in the last, but the radiating strie more 
distinctly visible. 
Fig. 7 «. A smaller individual of the same species. 
Position and locality. In the more shelly central part of the Trenton limestone at Middle- 
ville, Herkimer county. (State Collection.) 
137. 11. LINGULA CRASSA (x. sp.). 
Pu. XXX. Figs. 8 a, b,c, d, e. 
Broadly ovate, with a subacute beak ; one valve more convex than the other, and some- 
what arched; shell thick, marked by strong concentric elevated lines, without radiating 
strie. 
This shell is broad and regularly rounded in front, sloping abruptly to the beak. The 
thick shell and prominent concentric lines are characteristic. The shell is black, and less 
brillant than the Liyevtm usually are. I have seen but one perfect specimen. Single 
valves and fragments are abundant in the limestone at Basin Harbor ( Vermont). It is 
also apparently the same species, in fragments and smaller individuals, which sometimes 
abound in the silico-argillaceous limestone intercalated among the slates east of the Hudson 
river near Troy, showing its geological range to be from the Trenton limestone through 
the Hudson-river group. 
Fig. 8 a, b. View of both valves of this species. 
Fig. 8 c. View of the edge of both valves, closed; one being more convex than the other, and slightly 
arched, 
Fig. 8 d. A larger specimen, apparently of the same species, somewhat crushed. 
Fig. 8 ¢, A smaller specimen, apparently of the same species. 
Position and locality. This species occurs at Middleville, in the central part of the Trenton 
limestone ; also in the same rock at Basin Harbor and Crown Point on Lake Champlain. 
A species, similar or identical, in limestone among the shales of the Hudson-river group, 
near Troy. 
