I 250 DIPLODON 



DiPLODON TRIVIALIS. n. S. 



Shell elliptical or obovate, convex, subsolid, inec|uilateral, 

 nearly evenly rounded before and behind ; beaks moderately 

 full, raised somewhat above the dorsal line, which is incurved 

 in front of them, their sculpture numerous, fine, radial bars ; 

 posterior ridge scarcely developed ; surface unevenly, rather 

 finely sulcate ; epidermis black or dark brown, somewhat cloth- 

 like when fresh, subshining and tinted green when rubbed ; 

 left valve with two compressed pseudocardinals, the anterior 

 one sometimes feeble, and two remote, delicate laterals ; right 

 valve with two compressed pseudocardinals, the upper small, 

 and one lateral ; dorsal pits few, under the hinge and parallel 

 with it ; muscle scars shallow ; nacre bluish-white, often 

 blotched. 



Length 52. height 33, diam. 20 mm. 



Taboticabal, San Paulo, Brazil. 



This species is a little wider behind than in front and is 

 nearly evenly rounded at both ends. A number of specimens 

 were sent by von Ihering from the type locality. 



Group of Di plod on granosus. 



Shell elliptical to subtrapezoidal, somewhat compressed, 

 rather thin, beaks low, the sculpture irregularly radial, the 

 ridges narrow and sharp, separated by wide, trough-like 

 spaces, the outer in particular often becoming somewhat nod- 

 ulous or corrugated, the inner approaching and united below ; 

 surface sometimes slightly concentrically ridged and granose; 

 teeth delicate, compressed ; nacre bluish. 



Animal unknown. 



Dtplodon GRANosi;s ( r.ruguiere). 



Shell long elliptical or subrhomboid, subcompressed to quite 

 convex, subsolid, inequilateral ; beaks neither high nor full, 

 having irregular, radial, granular sculpture ; posterior ridge 

 low, sometimes rounded, often slightly angular or biangulate, 

 ending behind in a blunt, rounded point below the median line ; 

 surface delicatelv. often unevenlv, concentrically sculptured, 



