96 
PALAEONTOLOGY OF NEW-YORK. 
133. 7. LINGULA QUADRATA. 
Pl. XXX. Figs. 4 a, b, c. 
Crania quadrata. Eichwald, 1829, Zool. specialis, Yol. i. pag. 273, pl. 4, fig. 2. 
Lingula quadrata. Eichw. 1840, Sil. Syst. in Esthland, p. 164. 
— — Id. 1840, Urwelt Russlands, heft 1, p. 15. 
— — Id. 1842, Ibid, heft 11, p. 58. 
— — Murchison and Verneuil, Geol. Russia and the Ural Mountains, Vol. ii. pag. 292, 
pl. 1, fig. 10. 
Equivalve, equilateral, broadly oval, depressed-convex ; sides nearly straight and parallel, 
or slightly curved ; extremities nearly equal in width, the first broadly rounded, cardinal 
extremity slightly narrower and somewhat angularly sloped; beak marginal, not prominent; 
exterior surface of the shell marked by strong concentric striae, and along the middle by 
distinct longitudinal striae, which are equally visible when the outer shell is exfoliated. A 
longitudinal depressed line marks the shell from the beak nearly half way to the base. 
This species is perhaps the largest fossil Lingula known : it is distinguished by its 
general elliptical form and nearly parallel sides. In its dimensions it is near the Lingula 
Lewisii ( Sowekby ); but it is more regularly rounded at the base, and does not. present the 
square outline which that shell has. Our largest specimen is one inch and a half in length, 
with a width of almost an inch. 
The usual length of this shell is one inch, and its great size alone is commonly sufficient 
to distinguish it from any other species in our strata. The longitudinal stria; mark only the 
central part of the shell, and are equally distinct when the shell is exfoliated : this character 
may be useful in detecting the species. 
Our shell is evidently identical with that of Russia, as cited above, both from the figure 
and description, and from the opinion of M. de Verneuil, who has seen the Trenton 
species. 
Fig. 4 a. A specimen of the ordinary size; the shell partially exfoliated, and presenting the strong 
radiating stria; along the centre. 
Fig. 4 b. View of the edge of the shell, with the two valves closed. It appears slightly inequivalve from 
compression. 
Fig. 4 c. A specimen of larger dimensions, from which the shell is partially exfoliated. 
Position and locality. This species occurs in the central and higher part of the Trenton 
limestone, usually in the compact dark layers, unassociated with other fossils. In some 
instances, it occurs in the higher gray rock. Trenton Falls, Middleville, Turin, Lowville, 
and other localities in New-York. It has a wide geographical range, being known in Ohio 
and Wisconsin, where its geological position is similar to that in New-York. Its occurrence 
in several localities in Russia proves its distribution over an immense area in the palaeozoic 
seas. 
