UN 10.— Plate LXXVII] 



(leratt'ly ventricose, somewhat olive-coloured, indis- 

 tinctly rayed, smootli, wedge-shaped behind, I'roiit 

 dorsal edge convex and moderately sloping ; ventral 

 edge convex, scarcely in the least indented, arching 

 upwards in front, umbonal ridge angulated, hinder 

 area flattened, umboes broad, liuiule large and exca- 

 vated, nacre livid white, hinge margin broad, car- 

 dinal teeth pyramidal, lateral teeth thick. 



Conrad (as of Eaf.), Mon. p. 49. pi. 20. 



Hnb. Michigan, etc., N. America. 



According to Lea, this is identical with the criissiJens 



of Lamarck ; it is necessary, at all events, to delineate 



a shell wiiich bears no resemblance to our figure of that 



species. 



Species 409. (Mus. Ilanley.) 

 Unio consangdineus. Un. tedd parvd, maxinie iiiaqid- 

 laleraU, ovato-elongatd, atdice solidd veidrkond el 

 truncatd, postici tenui gradatim depressd d suhat- 

 tenuald, luted concolore, lavigatd, could umbonnli 

 nulla, hinuld salts magna et excavatd, margbie cardi- 

 nali lalissimd, denlibiis cardinaUbus pp-amidalihus, 

 sulcalo-lacinialis. 

 The kindred Unio. Shell small, extremely inequila- 

 teral, elongated-ovate, in front solid ventricose and 

 truncated, behind thin, gradually depressed and 

 somewhat tapering, of an uniform dirty yellow ; with- 

 out umbonal ridge ; lunule tolerably large and exca- 

 vated, hinge-margin very broad, primary teeth pyra- 

 midal, jagged and grooved. 

 Lea, Proc. Ac. K S., Philad. 18IU, p. GO ; Obs. on Unio, 



vol. viii. p. 71.pl. 7. f. 317. 

 Hab. Alabama and Georgia, N. America. 



A heavy little shell, closely allied to decisiis and its 

 allies, yet clearly distinct. It is cuneiform in convexity, 

 has the valves peculiarly shallow, and the muscular scars 

 pre-eminently impressed. The teeth of the left valve being 

 large and almost united at their origin, leave a peculiarl\ 

 shaped undivided and capacious receptacle for thein in 

 the opposite hinge. The umboes of adult examples are 

 almost invariably eroded. 



tongd, liiiiid pecidiari/er inaijiiilater/ili, valldd, sub- 

 venlricoxd, Uni, olicari'U (scu sordide viridij, radik 

 oiigmlis pa/lldioribus undiqua ornatd, margbie ven- 

 Iruli vix iidnbiu: retuso, cosld nmbounli iticonspieud, 

 lunula nullu, umboiiihus satis eminetdibus el plicis 

 ptiucis oblitjuc uiidulalis, margarUa albido-carules- 

 canle, deidibns latcrullbus nullis, deulc cardbiali in 

 valvulu dexlrd coidco-lriangulari, dnde curd'iunti an- 

 tico in valmdd sbtislrd postico iiwjorc. 

 The pebble Unio. Shell small, ovate or ovate-oblong, 

 not especially inequilateral, strong, subventricose, 

 smooth, olive (or dirty green), with very pale narrow 

 rays over its entii-e surface, ventral margin scarcely 

 at all indented, umbonal ridge not marked, no lunule, 

 the moderately prominent umboes wav6d with a few 

 slanting folds, nacre bluish-white, no lateral teeth, 

 primary tooth in the right valve conic-triangular, 

 front one in the left valve larger than the hinder. 

 Lea, Trans. Amer. Ph. Soo. vol. iii. (and Obs. on l^nio, 

 vol. i. p. 7), pi. 3. f. 1. 



.Ilasiiiodunlu Iruncata, Conr. not Say (teste Lea). 

 Hab. Ohio. 



Suspiciously close to the less triangular forms of del- 

 loidea, although adult examples can readily be discrimi- 

 nated. Lea points out that in the allied species it is the 



Species 410. (Mus. Ilanley.) 

 Uxio calceola. Un. testa pared, orald, vel ovato-ob- 



Speeies411. (Mus. Hanley.) 



Unio coevus. Uh. Icsid parvd, crassiusculd, suhocali, 

 poslice sMuaigulald, vi^ subventricosd, fused conco- 

 lore, nisi supra costam uuiboualem subangulatam sub- 

 hccigald ; ared dorsali posticd Ibis obliquis supeme 

 sparsbn corrugatd, umbonibus erosis, hand embienti- 

 bus, margardd ulhidd, dentibus cardbialibus mognis, 

 couico-lrinngularibus. 



The crow Unio. Shell small, thickish, somewhat oval, 

 subbiangulated behind, scarcely even subventricose, 

 of an uniform dark brown, almost smooth, except be- 

 yond the somewhat angular umbonal ridge, behind 

 which there are a few slanting raised wrinkles near 

 the beaks; umboes eroded, not projecting; nacre 

 whitish, primary teeth large, conic-triangular. 



Lea, .Jouru. Ac. N. S., Philad. ser. 3. (and Obs. on Unio, 

 vol. vii. p. 35), pi. 27. f. 97. 



Hab. Georgia, N. America. 



