269 



Fig. 191. Cypricardinia indenta. Left and right valves, enlarged to three diameters. 



distinct on left valve; rounded umbonal slope of right valve, 

 and sub-angular umbonal slope of left valve; strong, une- 

 qually distant concentric undulations and finer stri.i- : 

 radiating stria 3 , and a second set of stria' vertical to the 

 concentric lamellae. 



Found in the lower two feet of the Moscow shale, at Sec- 

 tions 4 and 5 (one specimen) ; in the Demissa bed, at Section 

 5 (abundant) ; also in the shale and limestone beds between 

 the Trilobite and Strophalosia beds (fairly common ). 



Genus ELYMELLA. Hall. 



[Ety. : Elymos, a case.] 

 (1885 : Pal. K Y., Vol. V., Pt. I., p. 1.) 



Shells with equal inequilateral valves, ovate-elliptical in 

 outline. The anterior end is short and rounded, the poste- 

 rior end narrower and rounded at the extremity. Closely 

 incurved beaks ; prominent umbones ; a short cardinal line : 

 and concentric lines of growth, which are sometimes lamel- 

 lose, — mark this genus. 



Elymella nuculoides. Hall. 

 (Fig. 192.) (Pal. N. Y., Vol. V., 

 Pt. I., p. 503, PL XL.) 



Distinguishing Characters. — 

 Small size ; obliquely ovate outline ; 

 regularly curving margins; hinge 

 line straight, a little less than half 



" Fig. 192. Elt/mrlhi uucirfoidrs. 



the length Of the Shell ; fine COllCeil- Specimen, retaining both valves in 

 ° conjunction, from Hamilton gi 



trie stria?, fasciculate on the surface ( from Hal1 )- 

 of the shell, giving rise to strong undulations. 



group 



