U N I 0. 



Plate XC. 



Speeics ■184. (Copied from Lea.) 

 Unio isotAHiuoiDEs. U)i. leslft ptirr/t, vix crassiiisciild, 

 iiiflat(i, valde hiaquitnterali. subqunJratd, iiiffnie re- 

 titsd, ad umbones tuiiiidd, aiiiice triinmid, tenehroso- 

 oUvaced concolore, iiiipoUld, lav'ujald ; cosid iiudionali 

 nngulatd, area dorsali posticd laid et plaimlatd ; iiali- 

 bits eminentibus iiiclbiatis et recicrvatk, concavi/a/e sid- 

 ciforml radlaute prtecessis ; lunuld laid; iiiargarild 

 a!bd et iridescenle ; deiitibus eanliiialibm bmibux, 

 traii-ifersix, compress is, crenatis, in idrdqne ralnild 

 2 ; lainelUs lateralibm nullis. 

 The Isocardian Unio. Shell small, scarcely even 

 thickisli, inflated, very inequilateral, subquadrate, re- 

 fuse beneath, swollen at the umboes, truncate in 

 front, of a uniform dark olive, dull, smooth ; um- 

 bonal ridge angular; hinder dorsal area broad 

 and flattened ; beaks prominent, recurved and in- 

 clined, preceded by a radiating groove-like conca- 

 vity; lunule broad; nacre white and iridescent; two 

 short transverse compressed crenated primary teeth 

 in each valve ; no lateral lamellae. 

 Lea (Pltiffiodoii), Journ. Ac. Nat. Sc. Philad. ser. 2. vol. 



iii. (Obs. on Unio, vol. vi. p. 38), pi. 32. f. 32. 

 Ifab. Rio Plata. 



A remarkable shell, described from a single individual, 

 and constituted a genus of, by Lea. The hmule is 

 marked with several impressed parallel transverse lines. 



Species 485. (Copied from Lea.) 

 Unio Dunkekianus. Uu. testd hand crnnsd, magis mi- 

 HUsve venlricosn, oblongo-elliplicd, inrpqnilateraU, sii- 

 perw ulrinqne angidatd, )iitidd,fiisco-nigreiscei>te, con- 

 ceidrice sidjrtigosd, umbonibus costis obliqiiis satis 

 viagiiif onialis, costd umbonali rotundatd, natibtis 

 proiiiiiiulis, margaritd alba ; dentibus cardinalibus 

 lotigia, coiiipressis, in valvidd dextrd 2 ; lamellis late- 

 ralibiis prodiictis, siibrectis. 

 Dunkek's Unio. Shell not thick, more or less ventri- 

 cose, oblong-elliptic, inequilateral, angulated at each 

 end of the dorsal edge, glossy, blackish-brown, some- 

 what wrinkled concentrically; umboes adorned with 

 somewhat large oblique ribs, umbonal ridge round- 

 ed, beaks a little projecting, nacre white ; primary 

 teeth long, compressed, two in the right valve ; la- 

 teral lamellae produced, straightish. 



Lea, .Journ. Ac. Nat. Sc. Philad. scr. 2. vol. iii. (Obs. on 



Unio, vol. vi. p. 25), pi. 28. f. 20. 

 Hab. Itio .Janeiro (Dunker), and New Granada (Ver- 



reaux). 



Species 480. (Copied from Lea.) 



Unio Poeyanus. Un. festd crassiusculd, si(bcylindraced, 

 in medio retmd, hirequilaterall, arcuatim elongato-ob- 

 longd, inferue iiicurvatd, entice brevi sed porrectd, 

 lilted seu luteo-olivaced, postice lavigatd, antice con- 

 cetitrice striatd, coda umbonali leviter siibcariiintd, 

 uatibus proiniiiuliis, liaud imdulatis ; mnrgarild fiaves- 

 cente ; dentibus cardimilibiis aubcompressis, cri'imlatis ; 

 lamellis lateralibiis rectis, productis. 



Poey's Unio. Shell thickisli, subcylindraceous, retusc 

 in the middle, inequilateral, curved elongated-oblong, 

 incurved veutrally, short but projecting in front, yel- 

 low or olive-yellow, nearly smooth behind, concen- 

 trically striated in front; umbonal ridge slightly sub- 

 carinated ; beaks a little prominent ; not undulated, 

 nacre yellowish ; primary teeth somewhat compressed, 

 crenulated; lateral lamellae straight, produced. 



Lea, Journ. Ac. Nat. Sc. Philad. ser. 2. vol. iii. (Obs. on 

 Unio, vol. vi. p. 35), pi. 32. f. 30. 



Hab. Eio de las Balsas, near Coyucan, Mexico. 



The surface is most minutely granular. 



Species 487. (Copied fi-om Lea.) 

 Unio Wiieatleyanus. Uh. testa crassd, ventricosd, sub- 

 elUplicd, subineeqiiilaterali, postice subbiaiirjitlatd, iii- 

 feriti siibarciiatd, tenebroso-olivaced, sublavigatd, ad 

 umbones costis divergentibus radiatd, costd umbonali 

 obtuse angulatd, natibits prominiiUs, lunuld aid nulla 

 vel incouspicud, murgnrild alhidd seu earned ; denti- 

 bus cardinalibus mngnis, crciinlatis, in utrdque valvuld 

 2 ; dentibus lateralibiis i-nlidis, productis, obliquis. 

 Wheatley's Unio. Shell thick, ventricose, somewhat 

 elliptic, somewhat inequilateral, subbiangular pos- 

 teriorly, somewhat arched veutrally, dark olive, 

 smoothish, rayed at the umboes with diverging ribs ; 

 umbonal ribs bluntly angidar, beaks a little project- 

 ing, lunule, if any, inconspicuous, nacre whitish or 

 flesh-colour; primary teeth large, crenulated, two in 



September, J868. 



