CORALLINE LIMESTONE. 



329 



specimens which do not possess these characters, and the shell is then not easily distinguished 

 from those in the Niagara group. This is peculiarly true of specimens collected in the Niagara 

 limestone in the eastern part of Wayne county, and in Cayuga county, where they have not the 

 full development vrhich the same species has in the shale at Rochester, Lockport, and elsewhere. 

 It is the most common brachiopod in this limestone. 



Fig. 10 a, b, c. Views of the ventral valve in several specimens of different size. 



Fig. 10 d, e, f. Front views of the same specimens, showing the indentation. 



Fig. 10 g, h. Dorsal valve and cardinal views of another specimen. 



Fig. 10 i, k. Dorsal and ventral views of a larger individual, where the indentation is scarcely 



perceptible. 

 Fig. 10 /, m. Profile views of fig. 10 i and fig. 10 k. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of John Gebhard junior.) 



688. 59. ATRYPA LAMELLATA. 



Pl. LXXIV. Fig. lla-A. 

 Compare Jltrypa rugosa and A. nodostriata, page 271 and 272, plate 56 of this volume. 



Sub-rhomboidal, the ventral valve more convex ; beak of the dorsal valve incurved, small, 

 acute and prominent ; surface marked by six or seven plications on each side of the mesial lobe 

 and sinus, which are simple from their origin ; mesial sinus marked by two plications, with 

 three corresponding ones on the opposite valve (rarely three plications in the sinus, and four 

 on the corresponding elevation) ; plications crossed by strong imbricating lamellae, which are 

 deeply arched, giving the surface a rugose aspect. 



This species bears a close resemblance to Ji. rugosa cited above ; but all the specimens 

 examined are nearly uniform in size, and not so large as the larger ones of that species. The 

 plications also are simple from their origin, though marked by imbricating lamellae much in 

 the same manner. 



Fig. 11a. Ventral valve of a full grown specimen. 

 Fig. 11 b. Several plications enlarged. 



Fig. lie, d. Ventral and front view of a smaller specimen. 

 Fig. 11 e, /. A specimen showing scarcely any sinus or elevation. 



Fig. 11 g, h. Profile views of different specimens, the lower figure perhaps flattened from com- 

 pression. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of JowN Gebhard junior.) 



