NO. 1205. SYXOPXIS OF TUi: X.U.lliKSHIMPSOX. 575 



(Group of 2/ampsilis amphichcenus.) 



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 part of 

 the posterior end like that of Schizoihwrm; 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 (Lampsilin) amphic.hwnus FRIERSON, Nautilus, XI, 1898, p. 10, pi. I. 



((Iroup of -Lampsilix 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; i>seudocardinals often almost want- 

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

 shell; nacre coppery to purplish; female shell not inflated at post 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. 1 



*Unio (Leptodea) leptodon RAFINESQUE, Ann. Gen. Sci. Phys. Brux., 1820, p. 

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



'Unio leptodon SAY, Am. Couch., VI, 1834. * CONRAD, New F. W. Shells, 1834, p. 

 70; Monog., 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, 

 tigs. 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. Phila., VI, 1853, p. 262. 



* JnodonpurpurttscensSwAixsos, Zool. 111., 1st ser., Ill, pi. CLX, 1823. * CATLOW 



and REEVE, Conch. Norn., 1845, p. 67. 



* Unio relnm SAY, New Harm. Disseminator, II, September 23, 1829, p. 293; Jan- 



uary 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 tenmssimus of Lea. 



