UNIO.— Plate LXXXIV. 



bus, et ill seriebus curvatis confertim ordinatis) luteo- 

 virescenle, aiit concolore, aid obscure radiald; mar- 

 gine venfrali retitso, lunula, aid nulla, aid perjmrvd, 

 viargardd alba, dentibus canUnalibus subtriijoiiis, 

 slriatis ; dentibus lateralibiis rectis. 



The seemly Unio. Shell depressed, thickish, squarisli 

 oboval, nearly equilateral, biangulated behind, every- 

 where subgranulated by minute tubercles (which, 

 beyond the bluntly angular umboual ridge, become 

 linear, and are disposed in curved and crowded 

 parallel rows), greenish-yellow, at most indistinctly 

 rayed ; ventral edge indented, lunule either raiiuite 

 or none, nacre white, primary teeth subtriangular, 

 striated ; lateral teeth straight. 



Lea, Proc. Ac.N. S. Philad. 1862, p. 168 ; Obs. on Unio, 

 vol. ix. p. 29. pi. 31. f. 276. 



Hnb. Texas. 



Very like Foiskei/i, but with much smaller tubercles, 



and more depressed and quadrate form. The sculpture 



reminds one of Say's apiculatiis. 



Species 448. (Copied from Lea.) 

 Unio Uruguayensis. Un. testa crassiiisculd, iiijlutd, 

 obovali, postice biangulaid, subceguilafei-ali, politd, 

 idrinqne coiicentnce subsulcatd, in medio lavi, viridi- 

 fuscd, obsolete subradiatd; margine ventrali subar- 

 cuato antice acclivi ; cosld nmbonali eminente rotmi- 

 datd, lunula perparvd, area posticd laid, natibus costis 

 divergentibus ornatis; margaritd albd, dentibus cardi- 

 nalibus crenatis et sublamellaribus, dentibus lateralibus 

 sfriatis et siibrectis. 

 The Ukdguay Unio. Shell thickish, inflated, oboval, 

 biaugular behind, subequilateral, polished, concentri- 

 cally subsulcatcd at each end, smooth in the middle, 

 greenish-brown, with very indistinct rays ; ventml 

 edge somewhat arched, rising in front ; umboual 



ridge prominent and rounded, lunule veiT small, 

 hinder area broad, beaks adorned with divergent 

 ribs, nacre white, primary teeth crenulated and some- 

 what lamellar, lateral teeth striated and straightish. 



Lea, Obs. on Unio, vol. x. p. 24. pi. 45. f. 298. 



Bab. Uruguay. 



Near delodoidns, but not so wide, and has a smooth 

 and darker epidermis; it is more veutricose and more 

 eDiptical than Wyiiianii. The colour is darkest pos- 

 teriorly. 



Species 449. (Mus. Lea.) 



Unio Wymanii. Uu. testd incequilaterali. obovali-siib- 

 quadratd, postice late biangulaid, depresad (et antice 

 iiiaxime), crassiiisculd, coiiceidrice subsulcatd (antice 

 prcBsertiin), olivaceo-nigrescente, vel concolore, wl ob- 

 scure radiatd, margine ventrali convexo ; costd nmbo- 

 nali prominuld, rotundatd; natibus parvis, plicis bre- 

 vibus subdivergentibus, radiatis, lunula incoiispicud, 

 margaritd albd; dentibus cardiiialibus angiiste subtri- 

 gonis, crenulatis; dentibus lateralibus longis, crenu- 

 latis. 



Wyman's Unio. Shell inequilateral, squarish oboval, 

 broadly biaugular behind, depressed (especially in 

 front), tolerably thick, concentrically subsulcated 

 (particularly in front), blackish-olive, at most indis- 

 tinctly rayed ; ventral margin convex, urabonal ridge 

 rather prominent and rounded ; beaks with small 

 divergently radiating ridges; lunule not evident, 

 nacre white ; primary teeth narrowly subtriangular. 

 crenulated; lateral teeth long and crenulated. 



Lea, Obs. on Unio, vol. x. p. 17. pi. 42, f. 2S9. 



Hab. fruguay. 



The shape is peculiar when combined with the radiating 

 folds. 



