U^'IO.— Plate LXXXV. 



lamellarihus, iransversis, cristatis, in valvi/ld sinktrd 

 ad basim conjmiclis. 



The truncated Unio. Shell thick, tumid, somewhat 

 concave before the middle, elongated, somewhat 

 wedge-shaped, pecidiarly inequilateral, broader in 

 front, somewhat tapering behind, sinuous ventrally, 

 glossy, dirty yellow, or yellow-olive with a few fus- 

 cous zones of increase, not rayed, nearly smooth ; no 

 umbonal ridge, umboes tumid and very prominent, 

 lunule deep, beaks incurved, nacre silvery white, pri- 

 mary teeth lamellar, transverse, crested, united at 

 their base in the left valve. 



Swains, Zool. Illust. ser. 2, Uuio, pi. 1. 



Hall. Kiver Tigris, near Bagdad. 

 The beaks are apparently simple. 



Species 454. (Mus. Hanley.) 



Unio arctior. Un. testd oblique elongato-oblongd, crassd, 

 depres.^a, antice brevi et angmte porrectd, postice at- 

 tenuaiiitt subbiangidatd, lutescente et olivaceo-viridi 

 obscure radiatd, conceiitrice substriald, margine ven- 

 trali convexo antice acclivi, costd timbonali subincon- 

 spicud, lunnld impressd, natibus aciitis porcis crassis 

 3-3 subconcentrice instructis, margaritd suhpurpnred, 

 dentibus cardinnlibus laciniatis, subtrigoiiiis. 



The much-pinched Unio. Shell obliquely elongated- 

 oblong, thick, depressed, short and narrowly pro- 

 jecting in front, taperingly subbiangular behind, ob- 

 scurely rayed with olivaceous green and dirty yellow, 

 concentrically substriated ; ventral edge convex and 

 anteriorly sloping upwards, umbonal ridge rather in- 

 conspicuous, lunule impressed, beaks furnished with 

 2-3 almost concentric coarse ridges, nacre pui-jjlish, 

 primary teeth jagged and triangular. 



Lea, Trans. Amer. PJiil. Soc. vol. vi. (Obs. on Unio, vol. 

 ii. p. 10), pi. 4. f. 10. 



Hah. Ohio, near Cincinnati, N. America. 

 ^'ery near gihbosns, yet of a different shape. 



Species 455. (Mus. Hanley.) 

 Unio multistriatus. Uh. te.<i1d parvd, cmnpreml, suh- 

 tenui, oblongd, anlice brevi, podice subbiaugiilald, oli- 

 vaced concolore (fernigine smpiim occuUald) rugis con- 

 feriis elevalis undiqne sculptd ; rugis antice et iiiferne 

 ■subconcentrice ordinalis, umbones versus autem ziczac- 

 formibu<i et pone costam umbonakm inconspicuam an- 



gidatim divergeyitibus ; margine ventrali subretuso, 

 margaritd aUjo-carulescente, nitidissimd, superne oli- 

 vaced, dentibu.s cardinalibus sitblamellatin. 



The many-striated Unio. Shell small, compressed, 

 thinnish, oblong, short in front, subbiangnlated be- 

 hind, of a unifoi-m olive (usually concealed by rust), 

 everywliei-e sculptured by raised and crowded wrink- 

 les, which are almost concentric in front and near 

 the base, are broken into ziczacs near the umboes, 

 and angulately divergent behind the obscure umbonal 

 ridge ; ventral edge somewhat indented, nacre of a 

 brilliant bluish-white, but olivaceous above, primary 

 teeth sublamellar. 



Lea, Obs. on Unio (Trans. Amer. Phil. Soc. vol. iv. I, vol. 

 i. p. 101.pl. 13. f. 22. 



Hab. Brazil. 



Now regarded by Lea as identical with the elUpticiis of 

 Spix, but if so, the shell (a very rare one in England) 

 merits to be figured from its very remarkable sculpture. 



Species 456. (Mus. Hanley.) 



Unio subovatus. Un. testa crassiuscuM, ventricosd, 

 oralo-subirigond, subinaguilaierali, antice roiiindato- 

 attemiatd, postice dilatatd, inferne arcuatd et antice 

 acclivi, sublavigatd, luted, radiis permultis obscure 

 viridibns undiqne ornatd ; costd umbonali vix angnlatd, 

 area posticd dorsali latd concaviusculd, ligamenlo 

 brevi el magna, umbonibus eminentibus, margaritd alba ; 

 drntihas cardinalibus in utrdque valvuld binis, anguste 

 trigonii, erectis ; lamellis lateralibus altis. 



The subovate Unio. Shell thickish, ventricose, subtri- 

 angvdarly ovate, somewhat inequilateral, rotundately 

 tapering in front, dilated behind, below arched and 

 rising in front, smoothish, everywhere adorned with 

 very many dusky green rays on a dirty yellow 

 ground ; umbonal ridge not angular, hinder dorsal 

 area broad and somewhat concave, umboes promi- 

 nent, nacre white; primary teeth two in each valve, 

 narrowly triangular, erect ; lateral lamellce high. 



Lea, Trans. Amer. Piiil. Soc. ser. 2. vol. iv. (Obs. on 

 Unio, vol. i.j, p. 128. pi. IS. f. 4G. 



Hab. Ohio. 



The beaks are stated to be undulated. This shell, 

 which closely approaches both occidens and uvatus, is not 

 the subovatus of Plate XX.XI., which is the true ventri- 

 cosus of Barnes. 



