■NIC).— r 



LXIV. 



ciito, margiiie renlrali. rectuaculu : latere niiticu breoi, 

 decUvi. 

 TllK Rusxrc I'NIO. Shell ovate, Mibcyliiulnral, gnrti in 

 parts, abovi: and at the sides diverge\itly granulated. 

 brif^ht copper-coloured witliiii, with thick, jasged 

 teeth; posterior side oblong, obscurely biangidar, 

 dorsal margin straight, lateral oblique, terminal be- 

 tween the angles truncated, ventral margin rather 

 straight; anterior side short, sloped. 

 Lea, Obs. on Unio, vol. vi. p. 14. pi. 25. f. 7. 



Unio tumidiilus. 

 llab. Siam, Lea. 



The ]\Iexican species, Unio pticij'cnis, which Morelet 

 has named U. crocodUonmi, is nuieli more ovate and acu- 

 minate than this. Unio titmkhdus of Lea I take tn be 

 the young of our species, as siiuwn in a specimen m the 

 collection ol'T. L. Taylor, Esq. 



Species 32.5. (Mils. Sowerby.) 



;i() JIARGARITIFERUS. Ull. lesld ohloiKJO-OVlltd, ('O)ll- 



pressd, isul/urcuatd,fusco-Hiijrescenti, iiitiin iilhidd, doi- 

 iihm anticis haud promiuentibiis, dentihiis post ids nullis; 

 latere poslico arcaato, ohliqiteprope wargiiiew dorsahiii. 

 depresso, marijine dorsali convexo, laterali decliri, ter- 

 miiio acHminato, margine veiitraH ad lerminiiM siirmm 

 acclici, medio depresso snhcontracto, niiitjoiidias ciipreis, 

 haud proiiiiiientibm ; latere inilico xidiprodiirlo, siib- 

 ijuadrato. 



Tnii rE.utL-BK.UtlNG Tnio. Shell obloug-ovatr, com- 

 pressed, ratiier arched, blackish-brown, whitish 

 within, anterior teeth not prominent, posterior teeth 

 none ; posterior side arched, obliquely depressed near 

 the dorsal margin, dorsal margin convex, lateral 

 margin sloped, end acuminated, ventral margin 

 sloped upwards at the end, middle depressed, sub- 

 contracted, umboes copper-coloured, not prominent ; 

 anterior side somewhat produced, subquadrate. 



DliAfAN.iNU, Moll. Ter. Fluv. p. 132. t. 10. f. 17^19. 



I believe this shell to be quite 

 atiis of Lamarck, which has pron 

 lateral teeih. 



umboes and thick 



Species 321). (.Mus. Sowerby.) 



o VENUSTUS. I'll, testa oriitd, mlidd, coiiiprcssd, la- 

 vigatd, Jlavldd, fusciis talis viridibics radlatd, iutus 

 al/id ; latere postico aiigulalo, wargiiie dorsali redo, 

 margine laterali (ililiiiiio. termian tmsnli aeiniiiiiato, 

 margine renlrali eoiirexiiiscnlo, ni,iljijnibii.s aeirr,iin(iti\ ; 

 latere postico snbrotnnda. 



i BEAUTIFUL Unio. Shell ovatc, solid, compressed, 

 smooth, yellow, rayed with broad green bands, white 

 within ; posterior side angular, dorsal margin 

 straight, lateral margin oblique, basal terminus acu- 

 minated, ventral margin rather convex, umboes acu- 

 minated ; posterior side rather rounded. 



1, Obs. on Unio, p. 4. pi. 11. f. 4. 



'). I'otosi, Missoiu'i ; Cincinnati, river Ohio. 



