330 rAL*OKTOLO«T or SEW-TOKS 



6S9. 60. ATRYPA sp ^ 



Pu LXXIV. Fig. I2«,fc,t. 

 Riiomboitlal ; surtaco cf ventral ralre marked by about 19 angular plications, three of which 

 are very slightly elevated in front ; scarcely visible concentric stria, 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 stria, features which eminently characterize the other species. 



Fig. 12 a. A fragment of stone, on which are grouped several specimens of the preceding specie* , 



with a single one of this species in the centre. 

 Fig, 12 h. Another view of the same. 

 Fig. 12 c Profile of the elevation of the stri*. 



Position and hcality. In the Coralline limestone at Schoharie. 



(Collectum tif Joax Gukaks jaaior.) 



ACEPILIL.1 OF THE CORALLIXE LIMESTONE, 



The following have not been seen in any other rock ; and tliough differing from those of the 

 Niagara group in the western part of the Stale, they are likewise equally distinct from those of 

 the Lower Helderbei^ limestones which succeed this rock. 



690. 10. TEfcLINOMYA? EQUILATERA. 



Pi„ LXXV. m^. I e ~J, 



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 

 obliquelv 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 strife, and 

 a distinct, rather deep, groove extending from the beak nearly to the posterior extranity. In 

 less perfect specimens, the nearly equal extremities and oval form are usually sufficient to 

 characterize the species. 



Fig. I a, K Similar views of two specimens, showing a siighi difference ia form, probabir due 



to pressure. 

 Fif. 1 c. Cardinal view of fig, 1 e. 

 Fig. 1 d. View of the posterior slope, showing lae groove in each vs.ve. 



Position and locality. In the Coralline limestone of Schoharie, 



{Coihdvm iif JoHS GebbajiI) jnaior.) 



