SPH^RIL'M. 



55 



Fig. 54. 



S. meridionale. 



S. modioliforme seems to be rare. It bears some resemblance 

 to S. meridionale, but it differs from it in being more inflated and 

 the color is lighter. 



34. Spliserium meridionale, Prime.— Animal not observed. 

 Shell small, trausversely-oblong, compressed, delicate, inequilateral; 

 anterior side narrow, sliorter ; anterior margin some- 

 what angular, posterior subabrupt, basal slightly 

 rounded ; beaks inclined towards the anterior, small, 

 calyculate, approximate at apex ; valves slight, com- 

 pressed, stride very regular and delicate, hardly per- 

 ceptible ; epidermis yellowish-brown, irregularly 

 mottled with large blotches of a much darker color ; 

 hinge-margin very slightly rounded, narrow, much 

 shorter than the basal margin; cardinal teeth ai- 

 minutive ; lateral teeth slight, the posterior tooth 

 much the more elongated. 



Long. 0.33; Lat. 0.20; Diam. 12 inches. 

 Hub. North America, at Panama. (Cabinets of Prime and Smithsonian 

 Institution.) 



Sph^rium meridionale, PraME, Proc. Acad. Nat. Sci. Phila. 1861,414. 



This species is easily distinguished by its very inequilateral 

 aad compressed shape. Compared with S. maculatum, it is larger, 

 its posterior margin is less abrupt, and its lateral teeth are larger. 



35. Spltaerium maculatum, MoRELET.-Animal not observed. 



Shell small, transversely-oblong, rhombic, elongated, inequilateral, com- 

 pressed, delicate ; anterior side much the narrower, 

 slightly rounded ; posterior side very broad ; posterior 

 margin abrupt, forming a straight line from the hmge 

 to the base of the shell; inferior margin nearly 

 straight; valves slight, very little convex; beaks 

 small calyculate, inclined towards the anterior side ; 

 slri^ not perceptible ; epidermis dark yellowish-brown, 

 irregularly mottled with spots of a much darker color; 

 hinge-margin nearly straight; cardinal teeth very 

 smaU ; lateral teeth strong, elongated. 



Long. 0.25 ; Lat. O.IS ; Diam. 0.12 inches. 



Hab. North America, in Yucatan. (Cabinets of Morelet, Jay, Prime 

 and Smithsonian Institution.) 



Cydas maculata, Morelet, Test. nov. Insul. Cub. etc. 1851, 25, pt. 2d. 



A rare species; the only specimens I have met ^vith were 



Fig. 55. 



5. maculatum. 



