NO. 1205. SYNOPSIS OF THE NAIADES— SIMPSON. 575 



(Qvowi) of Lampsilis am'plnchcenus,) 



Shell rather thin, elongate, elliptical, rounded before, pointed behind, 

 compressed, with a smooth, shining, black, rayless epidermis; beaks not 

 prominent, their sculpture unknown; there is a conspicuous gap at the 

 anterior base, and another very distinctly outlined at the upper i^art of 

 the posterior end like that of Schizothoerus; hinge line slightly curved; 

 pseudocardinals imperfect ; laterals compressed ; nacre purplish ; female 

 shell inflated at posterior base. 



Animal with large, elliptical palpi; mantle slightly thickened at the 

 edge; anal opening widely separated from the superanal, the latter large ; 

 foot large, hatchet-shaped. Several animals were examined, but all 

 were so much decayed that most of the characters could not be made out. 



tLAMPSILIS AMPHICH^NUS Frierson. 

 *U'.iio {Lampsilis) amphic.hanus Frierson, Nautilus, XI, 1898, p. 10, pi. i. 

 (droup oi Lampsilis leptodon.) 



Shell rather thin, elongate, elliptical, compressed, decidedly pointed 

 behind, the point raised above the center of the shell; beaks low, their 

 sculpture very feeble; there is a conspicuous post-dorsal wing in young- 

 shells, and sometimes vestiges of an anterior wing; young shell rather 

 dull and faintly rayed; there is a decided anterior basal and posterior 

 gap; hinge teeth very imperfect; pseudocardinals often almost want- 

 ing, even in young shells ; laterals faint, sometimes wanting in the adult 

 shell; nacre coppery to purplish; female shell not inflated atpost base. 



Animal with large, very thin, light brown branchiae, free nearly the 

 whole length of the abdominal sac; palpi large, thin, nearly semi- 

 circular; mantle thin, with a wide crenulate border; marsupium 

 projecting slightly below the inner gills. 



tLAMPSILIS LEPTODON Rafinesque.' 



*Unio {Leptodea) leptodon Eafinesque, Ann. Gen. Sci. Pliys. Brux., 1820, p. 

 295, pi. Lxxx, figs. 5-7. 



*Unio leptodon Say, Am. Couch., VI, 1834.— •* Conrad, New F. W. Shells, 1834, p. 

 70; Mouog., VII, 1836, p. 58, pi. xxxm.— * Chenu, Bib. Conch., 1st ser., Ill, 

 1845, p. 12, pi. I, figs. .5-7.—* KuSTEK, Conch. Cab. Unio, 1861, p. 197, pi. lxiv, 

 figs. 1, 2.— *SowERBY, Conch. Icon., XVI, 1866, pi. xlviii, fig. 257. — "" P^tel, 

 Conch. Sam., Ill, 1890, p. 157. 



* Symphynota leptodon Ferussac, Guer. Mag., 1835, p. 25. 



^ Leptodea leptodon Conrad, Pr. Ac. N. Sci. Phlla., VI, 1853, p. 262. 

 ^ Anodon pv/rpurascens^^NA.l^ss,o^, Zool. 111., Istser., Ill, pi. clx, 1823. — * Catlow 

 and Reeve, Conch. Nom., 1845, p. 67. 



* TJnio velum Say, New Harm. Disseminator, II, September 23, 1829, p. 293; Jan- 



nary 15, 1831 (newspaper form).—'' Ferussac, Guer. Mag., 1835, p. 28. — *L. W. 

 Say, Terr. & Fluv. Shells, 1840, p. 5. 



'This is one of the few species which its author has described so distinctly that I 

 feel sure there can be no doubt about it. Besides, his figure, such as it is, is some- 

 thing like the tenuissiimis of Lea. . 



