558 PEOCEEDINGS OF TEE NATIONAL MUSEUM. 



(Group of Lampsilis trahalis.) 



Shell solid, that of the male sinuate at post base, and sometimes pro- 

 duced i)Osteriorly, female shell wider, only slightly sinuous; beak sculp- 

 ture rather coarse, feebly doubly looped; epidermis dark, with wavy, 

 capillary rays; hinge heavy; nacre bluish-white or purple; animal 

 unknown.^ 



t LAMPSILIS TRABALIS Conrad. 



*Z7«io Irabalis Conrad, New F. W. Shells, May 3, 1834, p. 27, pi. iii, fig. 5; p. 

 72.— ^Ferussac, Guer. Mag., 1835, p. 29.— *Mollee,, Syn. Nov. Gen., 1836, p. 

 201. — *CoNRAD, Monog., XII, 1840, p. 110, pi. lx, fig. 2.— *Chp:nu, Bib. Concb., 

 Ist ser.. Ill, 1845, p. 15, pi. ii, fig. 3.—* Conrad, Pr. Ac. N.Sci. Phila., YI, 1853, 

 p. 259.—" B. H. Wright, Check List, 1888. 



t Unio troostensis Lea, Tr. Am. Phil. Soc, V, 1834 (August or September), p. 71, pi. 

 X, fig. 30; "" Obs., I, 1834, p. 183, pi. x, fig. 30.—* Fekussac, Guer. Mag., 1835, 

 p. 29.— *Hanlev, Test. Moll., 1842, p. 186; Biv. Shells, 1843, p. 186, pi. xxiu, 

 fig. 24. — Catlow and Reeve, Conch. Nom., 1845, p. 64. — *H. and A. Adams, 

 Gen. Rec. Moll., II, 1858, p. 496.—" Kuster, Conch. Cab. Uuio, 1861, p. 193, pi. 

 LXi, fig. 4. — " Sowerby, Conch. Icon., XVI, 1868, jd. lxxviii, fig. 406. — 

 *P^TEL, Conch. Sam., Ill, 1890, p. 170. 



^Margarita ( Unio) troostensis Lea, Syn., 1836, p. 21; 1838, p. 18. 



■^Margaron ( Unio) troostensis Lea, Syu., 1852, p. 25. 



*Margaron (Unio) troostii Lea, Syn., 1870, p. 39. 



'^Unio troostii B. II. Wright, Check List, 1888. 



•* Unio rannxemensis Sowrrby, Conch. Icon., 1866, pi. xxxix, fig. 216. 



Kentucky and streams of Tennessee; Clinch liiver, Virginia. 



i LAMPSILIS PERPURPUREUS Lea, 



* ZJwto jierpurpurens Lea, Pr. Ac. N. Sci. Phila., V, 1861, p. 41; * Jl. Ac. N. Sci. 



Phila., VI, 1866, p. 46, jd. xvi, fig. 44; * Obs., XI, 1867, p. 50, pi. xvi, fig. 44.— 

 * B. H. Wright, Check List, 1888. 

 *Margaron ( Unio) perpurpwreus Lea, Syn., 1870, p. 48. 



* Unio troostensis Sowerby, Concb. Icon., XVI, 1868, pi. Lxxix, fig. 415. 



Tennessee Kiver, drainage, extending into Virginia in the Clinch. 

 (Gi'oup of Lampsilis modioli for mis.) 



Shell elliptical, thin, quite evenly rounded before and behind, some- 

 what inflated; beak sculpture consisting of a few parallel bars, looped 

 in front, and generally open ; epidermis with beautiful, rather broad, 

 generally unbroken, sometimes slightly wavy rays; nacre brilliantly 

 iridescent posteriorly; teeth compressed. The female shell is greatly 



' Certain male shells of L. trahalis differ so remarkably from those of the females 

 and from any other known Naiades that it might be supposed that they belonged to 

 an isolated group. Other male shells, however, differ but little from the females, 

 and in L. perpurpureus, a species so close to L. trahalis that it is often difficult to 

 separate them, the male shells differ but slightly from those of the females. 

 Through this former species the group seems very closely related to that of ellipsi- 

 fonnis, and so on to the assemblage typified by L. iris. 



