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PALEONTOLOGY OF NEW-YORK. 
689. 60. ATRYPA- sp. 
Pl. LXXIV. Fig. 12 a, b, e. 
Rhomboidal; surface of ventral valve marked by about 19 angular plications, three of which 
are very slightly elevated in front; scarcely visible concentric striae, which are waved on the 
plications. 
This species occurs with the preceding, scarcely differing in form. In a single specimen the 
plications are more numerous, less raised on the mesial elevation, and almost destitute of con¬ 
centric striae, features which eminently characterize the other species. 
Fig. 12 a. A fragment of stone, on which are grouped several specimens of the preceding species, 
with a single one of this species in the centre. 
Fig. 12 b. Another view of the same. 
Fig. 12 c. Profile of the elevation of the striae. 
Position and locality. In the Coralline limestone at Schoharie. 
(Collection of John Gebhard junior.) 
AUEPHALA OF THE CORALLINE LIMESTONE. 
The following have not been seen in any other rock; and though differing from those of the 
Niagara group in the western part of the State, they are likewise equally distinct from those of 
the Lower Helderberg limestones which succeed this rock. 
690. 10. TELLINOMYA1 EQUILATERA. 
Pl. LXXV. Fig. 1 a-d. 
Cast of shell nearly equilateral, oval; anterior extremity more rounded than the posterior, 
which is sometimes slightly alate ; a distinct groove extends from the inside of the beaks 
obliquely backwards nearly to the posterior extremity, above and behind which the cast is 
more compressed ; surface showing faint marks of concentric striae. 
This species is the most common acephalous bivalve in this rock. It is always found in the 
condition of casts, which, when well preserved, show the impression of concentric striae, and 
a distinct, rather deep, groove extending from the beak nearly to the posterior extremity. In 
less perfect specimens, the nearly equal extremities and oval form are usually sufficient to 
characterize the species. 
Fig. 1 a, b. Similar views of two specimens, showing a slight difference in form, probably due 
to pressure. 
Fig. 1 c. Cardinal view of fig. 1 a. 
Fig. 1 d. View of the posterior slope, showing the groove in each valve. 
Position and locality. In the Coralline limestone of Schoharie. 
(Collection of John Gebhard junior.) 
