U N I 



Species 293. (Mus. Taylor.) 



Unio subtrigonus. JJn. testa, compressu, soUdd, subtri- 

 uiit/ulari, (data, lavi, peroldlijnd, olivaceo-fascd, iiit/is 

 alljd, supra palUde saliiioned ; latere postico supra in 

 alaia elevatam cuneatam expamo, infra ad terminmn. 

 rotimdato, margiiie ventrali aqualiler conve.fo ; latere 

 antico hrevissimo, margiue dorsali dertivi, lermhio ro- 

 tiiudo, umljonibtts Itsvibus. 



The suBTiiiGONAL Unio. Shell compressed, solid, sub- 

 triiiDgular, winged, smooth, very oblique, olive-brown, 

 within white, with the upper part pale salmon ; pos- 

 terior side expanded above into an elevated cuneatc 

 wing, rounded beneath at the end, ventral margin 

 equally convex ; anterior side very short, with dorsal 

 margin sloped, end rounded, muboes smooth. 



SOWEKBY. 



Hub. Siara. 



A certain equal convexity of surface and rotundity of 

 marginal terminations gives this shell a different appear- 

 ancc from others of the winged group. 



Species 293. (Fig. a, h, Mus. Taylor.) 



Unio lutf.olus. Un. testa oblonyo-ovald, crassd, convexd, 

 lavi, irreyvlariter concentrice rugatd, epidermide leiuii 

 luted vet olivaced indutd, viridi sjiarsim radiatd ; la- 

 tere postico prodiicto, oblique auffulato, ruargiiie dorsali 

 recliusculo, marylite laterali obliijuo, termino acumi- 

 i/alo, luargine ventrali utrinque sursum acclivi ; latere 

 antico bremisculo, rotunda, umboidhus uudnlalini rii- 

 r/atis, liffain.ento maximo. 



The yellowish Unio. Shelloblong-ovate, thick, curved, 

 smooth, irregularly concentrically wrinkled, covered 

 with a thiu yellowish or olive epidermis, rayed spa- 

 ringly with green ; posterior side produced, obliquely 



nnguhn-, dorsal margin rather straight, lateral mar- 

 gin oblique, end acuminated, ventral margin sloped 

 upwards on both sides ; anterior side rather short, 

 rounded, uniboes wrinkled in waves, ligament very 

 large. 

 Lamarck, Anim. sans vert. vol. v. 

 Unio siliquiiides ?, Barnes. 

 Unio injlatus ?, Barnes. 

 Unio lienosus?, Conrad. 

 The large specimen figured shows the normal form ni 

 this species, which seems peculiarly subject to the varia- 

 tion of a ventricose and stunted posterior margin, which 

 occurs in many species, and in many cases indicates the 

 female from the shell, as represented at Fig. G. 



Species 29-t. (Mus. Taylor.) 



Unio cariosus. Un. testd ovatd, subinfiatd, .wlidd, Icni, 

 pdUiili stramined, fusco fasciatd, intus albd ; lali're 

 piislii-o hilo, ohliqne ungnlaiu, sublritjono, maryine 

 diirvili eU'i-ato, maryine laterali obliqiio, terniino acu- 

 minata, maryine rentrali sursinn accVwi, medio con- 

 vexo ; latere antico anyiisfo, uiiibonibns rotnndis, Ite- 

 vibus. 



The decayed Unio. Shell ovate, subinflated, solid, 

 smooth, pale straw, banded with brown, white withiu; 

 posterior side wide, obliquely angular, subtriangular, 

 dorsal margin elevated, lateral margin oblique, end 

 acuminated, ventral margin sloped upwards, convex 

 in the middle ; anterior side narrow, uudjoes round, 

 smooth. 



Say, Enc. Am. Cat. t. 3. f. 3. 

 Unio oe/iracenis ?, Say. 

 I do not perceive any appreciable difference in the two 



above-named species as represented by specimens that 



have come under mv observation. 



September, 1867. 



