90 PALEONTOLOGY OF NEW YORK. 



nun. Another individual measures 27 mm. in length, 26 mm. in height, 

 hinge-line 18 mm. A right valve referred to this species has a, length of 

 20 mm. and a height of 18 mm., hinge-line 17 mm. 



This species differs from any known form of Crenipecten : it is like 

 Aviculopecten in external form and surface characters, ami resembles the 

 recent genus Pecten. 



Mr. Meek compares this species with Aviculopecten Coxanus, Meek and 

 Worthen, from the coal measures of Illinois and Nebraska, It is evident that 

 the crenulations of the hinge have not been previously observed. Except in 

 the hinge crenulations, this form has no other relations with the genus Creni- 

 pecten, and it may be found to belong to some genus vet undescribed, which 

 will include other species now placed with the Carboniferous forms of Aviculo- 

 pecten. 



In the original description of the genus, McCoy has not indicated the intimate 

 structure of the hinge, and it is not improbable that there are several generic 

 types among the species included in the Carboniferous forms of Aviculopecten. 



The right and left valves have not been found in connection, but their 

 association, and the absence of similar forms in the same beds, render the 

 identity nearly certain. 



Formation and locality. In the Waverly sandstone near Newark, Ohio. 



