1244 DiPi.onoN 



full, raised aboNc die dorsal line, their seulpture not seen; 

 growth lines rather strong, in some eases being elevated into 

 slight, concentric ridges ; epidermis dark olive, brown or black, 

 scarcely shining ; left valve with two lamellar pseudocardinals 

 and two remote laterals ; right valve with two compressed pseu- 

 docardinals. the upper smaller, and one lateral ; dorsal scars 

 numerous ; muscle scars impressed ; nacre bluish, a little thick- 

 ened in front. 



Length 55, height 2(j, diam. 22 mm. 



Uruguay ; Southern Brazil. 

 Unio calpira vok Tiii;ring, Arch, fiir Nat.. 1893, p. 98, pi. iv, 



fig. 9. 

 Diplodon caipira Simtson, Syn., 1900, p. 877. 



A nearly evenly elliptical form, sometimes a little rhomboid, 

 rather closely and finely, concentrically sulcate, and quite dark 

 colored. It seems to be close to D. eUipticus, but is not so 

 much pointed behind and lacks the post-basal inflation of that 

 species. 



DiPi.oDON Picuus Lea. 



"Shell smooth, elliptical, somewhat inflated, very inequilat- 

 eral, somewhat rounded behind and obliquely rounded before; 

 valves somewhat thick, slightly thicker before; beaks slightly 

 ' prominent ; epidermis shining, black, striate and obscurely 

 rayed or without rays, with rather distant marks of growth ; 

 ligament small and dark brown ; umbonal slope somewhat 

 raised and rounded ; posterior slope compressed, elliptical, with 

 an obscure furrow on each valve ; cardinal teeth rather small, 

 compressed, lamellar, oblique, single in the left and double in 

 the right valve ; lateral teeth rather long, somewhat thin and 

 curved ; anterior cicatrices rather small, well impressed, con- 

 fluent with the lower but distinct from the upper ; posterior 

 cicatrices confluent, rather large and slightly impressed ; dor- 

 .sal cicatrices well impressed and placed across the cavity of 

 the beaks ; cavity of the shell rather deep and wide ; cavity of 

 the beaks shallow and rounded ; nacre bluish-white and irides- 

 cent. 



T^ength t.8, height t.t, diam. .7 in." (Lea"). 



Uruguay River, South America. 



