182 PALAEONTOLOGY OF CALIFORNIA. 



This genus is apparently allied to the group of Mcgalodon and 

 Opis in the family Crassatcllidce, the form approaching remotely to 

 M. carinatus; while the hinge differs in all of its details so strongly 

 as to permit no doubts of its generic difference. 



Named in honor of Mr. J. G. Anthony, a gentleman whose 

 name is intimately connected with American fresh-water con- 

 chology. 



A. CULTRIFORMIS, 11. 8 

 PI. 30, Fig. 236, and 236 a. 



SHELL long, narrow, compressed, slightly curved and tapering 

 posteriorly; beaks acute, prominent, and placed very near the 

 anterior end, which is obliquely truncated above, regularly 

 rounded below; posterior extremity truncated obliquely up 

 wards and inwards; cardinal margin concave, basal broadly 

 convex. Surface marked by fine lines of growth, most marked 

 near the beaks, where they assume the character of distinct 

 undulations. 



Figure 236, natural size ; 236 a, a magnified view of the hinge. 

 Locality: Half a dozen specimens, mostly fragmentary; were found by Mr. 

 Mathewson, near MartiSez. 



UNIO, Retzius. 



U. PEXULTIMUS, n. 8. 

 PI. 24, Fig. 164. 



SHELL moderately large, subquadrate, compressed, bialate, 

 length and breadth nearly equal ; beaks subcentral (?) ; wings 

 nearly equal in height, the posterior a little the longest, slightly 

 curved on their upper margin and rounded at the ends, so as to 

 unite with the ends of the shell without forming an angle ; an 

 terior, posterior and basal margins regularly curved, the poste 

 rior basal portion being more produced than the anterior. Sur 

 face marked by faint lines of growth, rarely so distinct as to 

 produce ridges. Ligament robust. 



