FRESH WATER AND LAND SHELLS. 28? 



Wahlamat river, in Oregon. It differs in being a smaller species, in being more inflated, 

 and particularly so in the superior part. In thi- shell the umbonial slope is smaller from 

 the beaks to the posterior dorsal margin. In the Nuttalliana the upper portion of the 

 umbonial slope is flattened, but it enlarges towards the posterior basal margin, and there 

 makes the greater diameter. In the Californiensis the greatest diameter is about the 

 miildle of the disk, and there is a marked difference in the wing, which is by no means so 

 much elevated. 



Anodonta Tk \t twimana. PI. XXVI. Fig. 48. 



Testa Itevi, oblongd, subinflatd, inxquilaterali, e natibus lineatis; valoulis crasris; natibus prominulis, ad 

 apices minute undulatd; epidermide oirido-olivaced, rugoso-striatd ; margaritd argented el iridescente. 



Shell smooth, oblong, somewhat inflated, inequilateral, with a line from the beaks; valves thick; beaks some- 

 what prominent, at the tips minutely undulated; epidermis greenish-olive and roughly striate; nacre silvery and 



■ 



lfab. Carthagena, South America, John C. Trautwine, Esq. 



My cabinet and cabinet of the Academy of Natural Science. 

 Diam. .9, Length 1.."), Breadth 2.5 inches. 



Shell smooth, oblong, somewhat inflated, inequilateral, obtusely rounded before, subalate 

 behind, with a line from the beaks to the posterior margin; substance of the shell thick; 

 beaks somewhat prominent, submedial, at the beaks very minutely undulated; ligament 

 veryloDg and thin, not protruding above the dorsal line of the valves; epidermis greenish- 

 olive, and roughly striate, quite imbricate behind, without rays; umbonial slope elevated 

 into a carina; anterior cicatrices distinct; posterior cicatrices confluent; dorsal cicatrices 

 none; palleal cicatrix slightly impressed; cavity of the shell rather deep and rounded; 

 cavity of the beak very -hallow and subangular; nacre silvery white, with minute stria? 

 from the beaks towards the margin; iridescent. 



Remarks. — The friends of Mr. Trautwine owe to him the possession of this interesting 

 species, of which be brought many specimens, and liberally distributed them. It differs 

 from any South American species which has come under my notice. It is a much 

 -mailer species than An. trapezialis, Lam., rougher in the epidermis and more oblong. 

 Some of the specimens are somewhat greenish, others yellowish-olive. The triangular 

 fosset at the end of the ligament, so usual in the South American Naiades, i- very per- 

 ceptible in this species. 



In outline, it is allied to /c/rr/go»«, (Nobis.) 



Inodonta Whbatleti. PI. XXVI. Fig. 49. 



/ . dnnflali, gibbosd, valde insequilalerali, angulald, an 'ulariter 



■: valvuli elevatis, fere terminalibus } epidermidt me&, 



liatd; margaritd salmon tinctd et void, \te. 



Shell smooth, transverse, rniher inflated, gibbons, very inequilateral, angular behind, irregularly rounded 

 before; swollen, a little elevated and almost terminal; epidermis cinnamon-red and raj I 



salmon-coloured and vcrv iridescent. 



