U N I 0. 



Plate LXXXIV. 



Species 443. (Mas. Lea.) 



Unio per.eformis. Uii. testa cramuscidd, satis veiitri- 

 cosd, Hidjincequilulerali, oblique oliovatd, su/jlavigata, 

 viridi-nigresceulfi, hand radiatd ; wanjine Vujamentali 

 acclini ; casta umbonali subrotundatd obtuse subanyu- 

 lata, margaritd alba ; dentibus cardiiiatibus hand 

 mai/nis, compressis, crenulatis. 



The podch-shaped Unio. Shell tliickish, moderately 

 ventricose, somewhat inequilateral, obliquely obovate, 

 smoothisli, dusky gTeen, not rayed ; ligamental edge 

 rising ; urabonal ridge roundish, bluntly subangu- 

 lated ; nacre white ; primary teeth not large, com- 

 pressed, erenulated. 



Lea, Obs. on Unio, vol. x. p. ^'0. pi. 43. f. 292. 



Hab. Urugtiay. 



There are imperfect irregular undulations along the 



angle of the hinder slope ; these, however, may not be 



persistent. 



Species 444. (From Lea.) 



Unio gratus. Un. testa crassiusculd, subventricosd, in- 

 feqiiiloterali, postice dilatatd, satiiratiiis oUvaceo- 

 fiiscd, sublamgatu ; margine veutrali convexo ; margiiie 

 liganientali aeclivi ; costd umbonali subinjlatd et ro- 

 tund atd ; lunuld vix ulld ; jiatibus plicii brevibus ra- 

 dintis ; margaritd albd ; deutibus cardiualibus sub- 

 transversis ; deutibus lateralibus elongatis. 



The agreeable Unio. Shell thickish, subventricose, 

 inequilateral, dilated behind, very dark olive-brown, 

 smoothish ; ventral margin convex ; ligamental edge 

 rising ; umbonal ridge somewhat swollen and round- 

 ed ; scarcely any lunnle ; beaks rayed with short 

 folds; nacre white; primary teeth somewhat trans- 

 verse ; lateral teeth elongated. 



Lea. Obs. on Unio, vol. x. p. 18. pi. 43. f. 290. 



Hab. Uruguav, S. America. 



Species 445. (Copied from Lea.) 



Uxui PIGER. Vu. testa subtenui, ventricosd, subimrqui 



laterali, oboratd, postice latd et subbiaiigulatd, fusco 



uigresceute, obsolete subradiutd, larigatd ; costd urn 



bonali rotuudutd, emineute ; area postied latd, obscur 



sulcidn ; liiuiild angnstd ; margaritd albd; deulibiis 

 cardinatHius compressis, laiiiellaribus, crenulatis ; deu- 

 tibus lateralibus longis et postice curvatis. 



The fat Unio. Shell thiunish, ventricose, somewhat 

 inequilateral, obovate, broad and subbiangular be- 

 hind, dusky brown, at most indistinctly rayed, 

 smooth ; umbonal ridge raised and rounded ; hinder 

 slope broad and obscurely grooved, lunule narrow, 

 nacre white ; primary teeth compressed, lamellar, 

 erenulated ; lateral teeth long, curved at the end. 



Lea, Obs. on Unio, vol. x. ]). 23. pi. 27. f. 295. 



Ifab. Uruguay. 



Allied to Uruguayensis, but smaller, rather rounder and 

 with a darker and less shining epidermis. There are ves- 

 tiges of divergently radiating folds on the eroded umboes. 



Species 440. (Copied from Lea.) 



Unmo Gesnerii. Un. testd subaquilaterali, crassiusculd. 

 in/atd, ovali-subquadratd, postice biangulatd, nitidd, 

 concentrice sulcatd,fusco-nigrescente, obscure radiatd; 

 costd umbonali conspicud, obtuse angulatd ; lunula iii- 

 couspiciiii ; margaritd albd, srepius niargine subpur- 

 pureo ; (hnldjiis cardinalihus parvis, subtransversis, 

 subcomjircxsis, in utrdque valculd singulis ; deutibus 

 lateralibus nullis. 



Gesner's LfNio. Shell nearly equilateral, thickish, 

 swollen, squarish-oval, biangulated behind, glossy, 

 concentrically grooved, blackish -brown, indistinctly 

 rayed ; umbonal ridge conspicuous, bluntly angular ; 

 lunule scarcely evident; nacre white, usually bor- 

 dered with purplish ; primary teeth small, somewhat 

 transverse, somewhat compressed, one only in each 

 valve ; no lateral teeth. 



Lea (Margarifana), Proc. Ac. N.S. Philad. 1858, p. 138 ; 

 Obs. on Unio, vol. ix. p. 33. pi. 32. f. 280. 



Hab. Alabama and Georgia, N. America. 



Species 447. (Mus. Lea.) 



Unio speciosis. I'n. testd depressd, crassiusculd, sub- 

 quadrato-obovuli, snbaquilaterali, postice biangulatd, 

 midique tuierculis minutis subgranulatd (grants su- 

 pra costani untbonalem obtuse angulatum subliuean- 



