SPH^ERIUM. 



55 



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

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

 the color is lighter. 



34. Sphaerium meridionale, PRIME. Animal not observed. 



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

 anterior side narrow, shorter ; anterior margin some 

 what angular, posterior subabrupt, basal slightly Fig. 54. 

 rounded ; beaks inclined towards the anterior, small, 

 calyculate, approximate at apex ; valves slight, com 

 pressed, striae 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 di- s. meridionale. 

 minutive ; lateral teeth slight, the posterior tooth 

 much the more elongated. 



Long. 0.33; Lat. 0.20; Diam. 0.12 inches. 



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

 Institution.) 



Sphssrium meridionale, PRIME, Proc. Acad. Nat. Sci. Phila. 1861, 414. 



This species is easily distinguished by its very inequilateral 

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

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



Fig. 55. 



35. Sphaerium 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 hinge 

 to the base of the shell ; inferior margin nearly 

 straight ; valves slight, very little convex ; beaks 

 small, calyculate, inclined towards the anterior side ; 

 striae not perceptible ; epidermis dark yellowish- brown, 

 irregularly mottled with spots of a much darker color; 

 hinge-margin nearly straight ; cardinal teeth very 

 small ; lateral teeth strong, elongated. 



Long. 0.25 ; Lat. 0.18 ; Diam. 0.12 inches. 



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

 and Smithsonian Institution.) 



Cyclas maculata, MORELET, Test. nov. Insul. Cub. etc. 1851, 25, pt. 2&amp;lt;1. 



A rare species ; the only specimens I have met with were 



S. maculatum. 



