UNIO. 



Ferussac, in Rossmiissl. Icon. ]j. iind S. IMoll. ]it. 2. 

 p. 24. f. 134. 

 U„io tiepressa, Mulilf.-l.lt. 

 AInsniodoida comjirfsm, ileiike. 

 IMj. lllyi-ia. 



A full-sized e-tample has been figured, with the margin 

 less incurved than usual. The valves have a tendency to 

 liecome g-reeu at their hinder e.\.treraitics, and the minute 

 folds to be disposed in two series. 



I.ATE LXXIX. 



ini'ented, rising in front, unibonal ridge inconspi- 

 cuous, lunule undeveloped, umboes scarcely project- 

 ing, nacre dirty whitisii, primary teeth jagged and 

 subtriangular. 



Lea, Trans. Amer. Phil. Soc, ser. 2. vol. viii. (Obs. on 

 Unio, vol. iii. p. 38j, pi. 10. f. 12. 



ITai. Holston river, Tennessee, N. America. 



Although the characters are merely negative, the species 



can generally be recognized. 



Sp, 



415. l,:\Ius. Hanlev.) 



Figure 415, «hieh represents the male of U. Trons- 

 terisis (Plate LXXVllL), liaving inadvertently been num- 

 bered as though distinct, it lias been thought preferable 

 to consider that Species 415 represents one of those 

 shells (such as the pen/ij; of Phite XVIII.) which were 

 erroneously determined in the earlier portion of this mo- 

 nograph, rather than create further confusion by changing 

 the priuted-off references to no less than six lithographs. 



Species 416. (Mus. Hanley.) 



Unio aMCENUS. Uh.. testa pand, crassiuscida, sitbcentri- 

 cosd, suhiitcEqu'daterali, ovali, postice lavi et vix -iiii- 

 Inani/ulcdd, mtiild, squnUd'e Jlavd, radiis ollvaceis iii- 

 lerntplis undique fpo-itice aiitem coi/fertius) oniatd, 

 autice snbrugosd et minus pictd ; maiy'me veiitrcdi 

 siibretuxo antici acclki, costd umboiiaH iiiconspiciid, 

 liintdd vix ulld, timbonibus vi.v I'mineidibiis, mnrgnritd 

 squalide albidd, Jeidibns cardiiiulibii-< ■■subtri</oiiis, 

 laciidatis. 



The delicate Unio. Shell small, moderately thick, 

 soniewliat inequilateral, somewhat ventricose, oval, 

 smooth and scarcely subbiangulated behind, of a 

 shining impure yellow, everywhere (yet more closely 

 behind) interruptedly rayed with olive, less painted 

 aiul somewhat wrinkled in front ; ventral edge slightly 



Species 417. (^Ins. Hanley.) 

 Unio rROPlNUlVS. Un. testa pared, solidd, ob/iqite sub- 

 oibicidari, vatde iiirequdateruli, antici' tiii,iii!i:, Jrinde 

 concnvitate latissimd radiatd, postmno c/.c Miln-i'iih-i- 

 cusd, tided, olivaceo-viridi postice nidintiiii linrutd, 

 jilicis iiirremeiiti obliais tanliim scnlpta ; margilie 

 reidndi in uiediu nuiiienle, a/dice repenie acclivi ; 

 eostd iiiiiboncdi lata conspicnd, umboidbiis remotis, 

 eiiiinenlibiis, divergentibus, urea dorsali posticd an- 

 giistd, lunuld ma.rimd, margaritd albd, margine cardi- 

 nali lato ; dentibus cardinalibus in idrdqae valvi/td 

 binis, magnis, trigonis, liiciniatis. 

 The neighbouring Unio. Shell small, solid, obliquely 

 suborbicular, very inequilateral, tumid in front, then 

 raved by a vei-y broad concavity, finally scarcely 

 even subventricose, dirty yellow, with posterior ra- 

 diating lines of olivaceous green, merely sculptured 

 by the blunt folds of increase ; ventral margin pro- 

 jecting in the middle, suddenly rising in front; um- 

 boiial ridge liroad and conspicuous, umboes distant 

 and diverging, umbonal area narrow, lunule ex- 

 tremely large, nacre while, hinge-margin broad ; pii- 

 mnry teetli two in each valve, large, triangular. 



Lea, .louru. Ac. N. S. Philad. ser. 2. vol. v. (Obs. on 



Unio, vol. viii.), pi. 5. f. 212, 

 ]{ab. Alabama, N. America. 



Hetween jierplexiis and lliiiigiauas. The linear rays 

 vary in nuudjcr and closeness. 



