U N I 0. 



Species 320. (Mu>. Soweiby.) 



I'll, h'sfil parvd, ovalii, siilidd, pnllide 



AltATUS 

 iilirnci'n, concent rice Icnni-Hriitii, /, 

 politico proilucto, arcniitiiii iinijuliili 

 cOHVCro, le7-mino cenlnili. ncnminiilii 



■ latere 



llnrscli 

 rrnlnili 



siir.snm accVm ; latere antico Ijrwi, prope mnri/ineni 

 hniyalo, umhonihus parvis, hand proiiiinentiliHs. 



The ploughed Unio. Shell small, oval, solid, pale 

 olive, concentrically finely ribbed, white within ; 

 jiosterior side produced, with a curved ansjle, dorsal 

 margin convex, end central, acuminated, ventral mar- 

 . gin sloped upwards; anterior side short, smooth 

 near the margin, iimboes small, not prominent. 



Lea. Obs. on Unio, vol. iv. pi. 42. f. 12. 



.//„/,. •;- 



species 331. (Mus. Sov 



Unio sibglobosus. Vn. testa solid a, ocato-sidjrulnndd, 

 Hidilavigald, tnmidd, epidermide nigrescenti indutd, 

 intns salmoned, margine cardinati arcnato, dentiljiis 

 laceratis; latere postico prodiicto, angnlato, margine 

 diiiwali drcliri conre.ro, terinino tirisali acuminatu, 

 hiiirijine rentrali ante angnliim contracfo, turn con- 

 re.ru ; latere antico breoi, rotnndo, nmljonibiis iiiiiiidis, 

 hand prominentibns. 



riiE SUBGLODOSE Unio. Shell solid, ovato-subrotuud, 

 rather smooth, tumid, covered with a blackish epi- 

 dermis, salmon-tinted within, hinge margin archi'd, 

 teeth jagged; posterior side produced, angular, dor- 

 jal margin sloped, convex, basal end acuminated, 

 ventral margin contracted in front of the angle, then 

 convex; anterior side short, round, und)oes tumid, 

 not prominent. 



Lea, Obs. on Unio, vol. i. p. 142. pi. 2. f. 3. 

 Bayon Teche, Louisiana. 



Hah. 



This species is one of the most subglobose in form. 



Species 322. (Mus. Sowerby.) 

 NIO TRIGONUS. Un. testa subcompressa, subtrigona, 

 crnssa, siibltevigatd, fmco-olivaced, iiitvs albH, dentibns 

 maijnis laceratis, nmbonibus nndatis, prominentibns ; 

 latere postico siibqiiadrato, anguluto, margine dorsnli 

 et lafcrali declivibus, terinino basali snbtruncato, area 

 postangidari drpresw, margine centrali ante inignlnm 



siiliconlracto. medio siibdeprrsso ,■ latere antico breri. 

 ileclivi. ■ . 



The trigonal Unio. Shell subeomprcssed. subtrign- 

 nal. thick. .ralher smooth, olive-brown, white within, 

 w ith large jngged teeth, iimbocs undulated, promi- 

 nent ; posterior side subquadrate, angulaj-, dorsal and 

 lateral margins sloped, basal end subtruncated, post- 

 ang\dar area depvessed, ventral margin contracted in 

 front of the angle, middle siibdepressed ; anterior 

 side short, sloped. 



Lea, Obs. on Unio, vol. i. p. 120. pi. 10. L 40. 



Hab. Oiiio rivrr. at Cincinnati, and Louisville. 



Species 323. (Mus. Sowerljy.) 



Unio pykamidatus. Un. testa oblitjid pgramidatd, Irevi- 

 gatd. solidd, fn-ico-nigrescenti, intns .lalmoned, antice 

 crassd, postice tenni el iridescenti, margine cardinati 

 lato, crasm, dentibiis nuKjnis ; latere postirii iihliqne 

 prodiicio, rotiindatiin angiilalo, ante ungnlnni depresso. 

 terinino basali aciiminnto, inargiin' reiilrali versus Irr- 

 liiininn snbcoiit racto, medio tnmiilo. nmbonibus jicr- 

 elei-atis acuminatis, terminalibns : latere antico un- 

 rissiino, margine dorsali ante iimbiinex ciineulu. 



The I'Ykamidal Unto. Shell obliquely pynimiilMl, 

 smooth, solid, bhiekish-brown, salmon-tinted within, 

 thick in front, thin and iridescent behind, cardinal 

 margin wide, thick, teeth large; posterior side ob- 

 liquely produced, roundly angidar, depressed in front 

 of the angle, basal termination acuminated, ventral 

 margin subcontracted near the end, middle tumid, 

 umboes much elevated, acuminated, terminnl : ante- 

 ri(n- side very shcn't, dorsal margin euiieate in fmni 

 of the umboes. 



Lea, Obs. on Inio, vol. i. p. IIU. pi. IG. f 3!). 



Ilab. River Ohio. 



IMore elevated and oblique than Unio picnns. 



Species 324. (Mns. Taylor.) 



o RUSTICUS. Uit. testa ova la, subcglindraceft, partim 

 viridi, snpernc et ad latera divaricatim granijern, in- 

 tns rlvidi^ cnpred, dentibns crassis, laceratis ; latere 

 pos. 



3 oblongii. obscn 



lulerali oblinnn 



? bianyulato, margine dorsali 

 lerminali inter anqnios Irnn- 



