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CONCHIFERA. 

 Genus Aviculopecten McCoy. 



AvicuLOPECTEjsr GEADOCOSTUS (n. s.) Shell large, a little inequilat- 

 eral, broader than high ; left valve rather flat ; right valve more convex ; 

 umbones large, prominent, shell on the anterior slope bending abruptly 

 down to the anterior wing, which is faintly radiated. Hinge line and 

 full length of wings unknown. Surface marked by about twenty-five 

 broad, flat, compound ribs on the body of each valve, which are well 

 developed near the basal margin, but more indistinct on the umbones 

 and slopes. These ribs are separated by a narrow groove, and sur- 

 mounted by a distinct carina of about the same width as the groove, 

 giving the sides of the ribs somewhat the appearance of minute steps. 



Locality and position, in the sandstone of the Chemung beds at Bur- 

 lington, Iowa. 



Genus Caediomorpha DeKonnick, Caediopsis Meek and Worthen. 



Cardiomorpha (Caediopsis ?) paevirostris. Shell subcircular 

 in outline, slightly inequilateral ; valves broadly and moderately convex ; 

 base more broadly rounded than the front and oval margins ; beaks small, 

 incurved, pointing little, if any, forward. Surface marked by fine radi- 

 ating lines. ' 



This species is associated with C. ovata Hall, which Messrs. Meek 

 and Worthen regard as belonging to their genus Cardiopsis. If so, 

 our species should probably be referred to the same genus. It differs 

 specifically from that shell in its less oblique and more circular outline, 

 its much smaller umbones, and less incurved and deflected beaks. 



Genus Gervillia Defrance. 



Gekvillia strigosa (n. s.) Shell long and very narrow, posterior 

 end abruptly rounded, back slightly concave, base a little more convex 

 than the concavity of the back, most ventricose a little behind the um- 

 bones, one or two faint ridges running along the back on each side ; 

 anterior ear rounded at the front end, inflated, leaving an oblique 

 depression between it and the body of the shell, which reaches the 

 base, making it a little emarginate ; posterior ear small, and but slightly 

 elevated from the back of the shell. Surface marked by a few con- 

 centric wrinkles, more visible on the anterior parts. Length 4, 

 height 1. 



Locality and position, in the Chemung beds at Burlington, Iowa. 



ZOOPHYTA. 



Genus Zaphrentis Rafinesque et Clifford. 



Zaphrentis elliptica (n. s.) Coral in the form of an elongated, 



reversed cone, curved and laterally compressed, more so below than at 



the upper part ; sometimes this compression is so great as to produce a 



