24 
PALAEONTOLOGY OF NEW YORK. 
The shell-substance in Lingulops is exceedingly tenuous and not usually 
resolvable into layers. The fossils are generally preserved as thin white films, 
through which the thickened muscular area is plainly visible by its deeper 
color. Its color alone indicates that its substance is largely if not quite cal¬ 
careous, differing from Lingula in this respect, but agreeing with Lingulasma 
and the Trimerellids. 
Genus LINGULASMA, Ulrich. 1889. 
PLATE II, FIGS. 17-23. 
1889. Lingulasma, Ulrich. American Geologist, vol. iii, No. 6, p. 383, figs. 5 a, b, e, d( p. 378). 
Compare Lingula Canadensis, Billings, 1862. Paleozoic Fossils, vol. i, p. 114, fig. 95. 
Diagnosis. Shell sub-quadrate, linguliform, sub-equivalve; the brachial 
valve considerably the deeper. Beaks apical, cardinal margins gently sloping 
to the sides. 
Interior of the pedicle-valve with a low concave platform which extends 
over one-half the length of the shell, and is not hollowed on its anterior wall. 
The pedicle-area has been largely enclosed within the shell, making a distinct 
sheath or shelf, beneath which lie the apical portions of the central and lateral 
muscular scars. Crescentic scars scarcely defined. 
The brachial valve is deep, with a high platform of about the same extent as 
that on the other valve, sloping inward near its anterior margin and continued 
axially into a strong septum, which reaches nearly to the front of the valve. 
The anterior walls of the platform are broadly excavated, and close against the 
base of the septum are hollowed out into short conical cavities. The crescent 
is strongly developed and sharply pointed backward at its center. Its lateral 
curves are broad, reaching to the edge of the platform. Directly in front of 
its central angle lies a short, sharp, median ridge, which disappears near the 
center of the platform. Lateral and central muscular scars well developed. 
Type, Lingulasma Schucherti, Ulrich. 
Observations. This remarkable form serves as a most important connecting 
link between the palaeozoic Lingulas and the Trimerellids, following, in the 
