U N I 



I'LiTE XLVIH. 



Species 257. (Mus. Cuming in Brit.) 



Unio Leptouon. Uii. testa ienui, ornh', obloiiyd, han, 

 concent rice riigatd, pallidi viridi, in//ix pin-juin-d ; lu- 

 te re podico oblongo, obscure hiiuKjuhitu, Irrmine obli- 

 que tnincato, subtus acuminata, uianjine dorsali con- 

 vexd, niurgine venfrali rotundatim convexo, tenninibus 

 elevatis ; latere aritico brevi, rotundo, marrjine i/omali 

 brevisunio, twibouibns parvis, dentibns teuuhaintis tiab- 

 obmletis. 



The scale-toothed Unio. Shell tliiii, ovul, obloiip;, 

 smooth, concentrically wrinkled, pale-green, purple 

 within; posterior side oblong, obscurely biaugular, 

 the end obliquely truncated, acuminated beneath, 

 dorsal margin convex, ventral margin roundly con- 

 vex, raised at the ends ; anterior side short, round, 

 dorsal margin very short, uraboes small, teeth very 

 thin, rather obsolete. 



Rafinesque, ? 



Hub. ? 



Species 258. (Mus. Cuming in Brit.) 

 Unio semiquadrata. Un. testa compressd, tei/ui, sublri- 

 ijond, alatd, Jlavido-viridi, fasciia rlridib/is tribus pos- 

 tice radiatd, intits albido-carnh-\ci'iili\ ilnitibns latera- 

 libns lenninsimis ; latere poslini maijini, f.rpnnso, mar- 

 ijine dorsali in. cuneum elevato, termino rutnndo, mar- 

 gine veiitrali medio siibcontracto ; latere antico parvo, 

 angustato, margine dorsali recto, brevissimo, angidato. 

 The half-square Unio. Shell compressed, thin, sub- 

 trigonal, winged, yellowish-green, rayed posteriorly 

 with three green rays, bluish-white within, lateral 

 teeth very thin ; posterior side large, expanded, with 

 dorsal margin raised into a corner, the end rounded, 

 ventral margin somewhat contracted in the nnddle ; 

 anterior side small, narrow, dorsal margin straight, 

 very short, angular. 



SOWERBY. 



Hab. Camboja, Lao Mountains. 



Among the widely-alate species this is the most ex- 

 panded in proportion to its size. 



Species 259. (Mus. Cuming in Brit.) 

 lKCULA. ('n. testa soHdd,calde angulatd, . 



tumidd, snbtrigond, epldermide fiisco-nigricanti, viridi 

 radiatd indutd, intiis albido-purpnred ; latere posticu 

 injliito, ill angulmn magnum elevato, margine dorsali 

 subdeclici, termino acute biangulato, ligainento magna, 

 margine ceiitrali convexo ; latere antico angusto, ro- 

 fundi), margine dorsali depresso, niiihoiiibus magnis, 

 pcrelevalis, plicis magnis lindalis, dentibns laleraiibas 

 null is. 



The little ark Unio. Shell solid, strongly angular, 

 tliiek, tumid, subtrig.iual, invested with a blackisli- 

 brown, green-rayed epidermis, whitish-purple with- 

 in ; posterior side inflated, raised info a large, ele- 

 vated angle, dorsal margin rather sloping, acutely 

 biangular at the end, ligament large, ventral margin 

 convex; anterior side narrow, round, with dorsal 

 margin depressed, umboes large, much elevated, un- 

 dulated with large plaits, no lateral teeth. 



Lka on Unio, vol. ii. p. 71. t. 23. f. G9. 



llab. Georgia, in America. 



Eemarkable for its angular form 

 forming thick plaits on the umboes. 



ided knob- 



Species SCO. (Mns. Ci 



Unio Housei. Un. lestd mu, 

 lenni, alald, epiderinide niij 



roiiijiri: 



nbnrali. 



■iciinli 



■inlarili', 



ciitii iiidiihi, inhis piitlidi' piirjinred; latere postico ex- 

 paiisii, liiiiiniiiliilo, liTiiiinu sidilrniicato, supra angutos 

 alalo, iiiiirgine duisa/i dininciliin plicatd, margine 

 rrnlndi arciiafd ; latere antivu brrri, niurgine dorsal, 

 alalo. 



Holsl's Unio. Shell large, compr 



thin, winged, invested with a blackish, irregularly- 

 plaited epidermis, pale-purple within ; posterior side 

 expanded, biangular, subtruncated at the end, with 

 a wing above the angles, the dorsal margin diver- 

 gently plaited, ventral margin arched ; anterior sitlc 

 short, dorsal margin winged. 



' Lea, Unio, vol. ii. p. 7L t. 23. f. G!'. 



I llab. Georgia, in America. 



i 



The pecidiarity of this species in compiinson witli other 



I alate species is t'he plaited dorsal margm of the uing. 



