$78 
PALAEONTOLOGY OF NEW-YORK. 
margins bordered by a narrow rounded rim, which is separated from 
the body of the shell by a narrow groove. The anterior furrow is about 
halfway between the middle and the anterior end, extending halfway 
across the valve, curving a little backwards; while the posterior furrow 
is nearly central, extending about half the width of the valve, scarcely 
curving forwards, and not uniting with the anterior one. The space 
between the two furrows is occupied by a prominent node, which rises 
above the level of the surrounding surface. 
Surface, except the furrows and base of the node, granulose. 
This species is well marked in its regular form, nearly equal extremities, and 
beautiful granulose surface. 
Fig. 1 a. The specimen, natural size. 
Fig. 1 h. The same enlarged four diameters. 
Fig. 1 c. Profile view of the same. 
Fig. 1 cl. A portion of the surface magnified, showing the granulose character. 
Geological position and locality. In the pentamerus limestone of the Lower Hel- 
derberg group : Schoharie county. 
Beyricliia ocnlina (n. s.). 
Plate LXXIX B. Fig. 2 a - e. 
Carapace semioval, length little greater than the height, slightly contracted 
on the hinge-line : posterior furrow deep, nearly central, extending 
from the hinge-line more than halfway to the base, and curving slightly 
forwards ; anterior furrow shorter and more shallow than the posterior, 
curving around the subcentral node above, but not reaching the hinge 
margin, and in its lower extension curving backwards and becoming 
more shallow, scarcely uniting with the posterior furrow. Posterior 
lobe sometimes with a transverse depression and the upper extremity 
becoming more prominent, and sometimes extending above the hinge¬ 
line, its entire width above being nearly equal to that below : anterior 
lobe depressed and narrower near the hinge-line, and spreading below. 
Body of the test separated from the inner border by a narrow groove, 
