NO. 1205. SYNOPSIS OF THE NAIADES— SI2IPS0X. 669 



doubly looped and swollen ou the well-developed posterior ridge; sur- 

 face rayed; pseudocardinals compressed, reflexed; laterals single, 

 double, or triple in each valve. 



Animal with branchial opening having a few coarse papillai; anal 

 opening smooth, or with very fine crenulations. 



tALASMIDONTA HETERODON Lea. 



* Unio heterodon Lea, Tr. Am. Phil. Soc, III, 1830, p. 428, pi. viii, fig. 11 ; * Obs , I, 



1834, p. 42, pi. VIII, fig. 11.— "CONKAD, New F. W. Shells, 1834, p. 69.— 

 * Ferussac, Guer. Mag., 1835, p. 26.—* Desha yes. An. sans Vert., 2d ed., VI, 



1835, p. 548; 3d ed., 11, 1839, p. 672.— * Conrad, Monog., X, 1838, p. 90, pi. 

 XLix, fig. 3.— *Hanley, Test. Moll., 1842, p. 183; Biv. Shells, 1843, p. 183, 

 pi. XXI, tig. 42. — *Catlow and Reeve, Couch. Norn., 1845, p. 59. — * Conrad, 

 Fr. Ac. N. Sci., Phila., VI, 1853, p. 250.—* Chenu, 111. Conch., 1858, pi. xvi, 

 figs. 2, 2a, 2b.—* H. and A. Adams, Gen. Eec. Moll., II, 1857, p. 495.— "Kus- 

 TER, CoQch. Cab., 1861, p. 192, pi. lxi, fig. 2. — * Sowerby, Conch. Icon., XVI, 

 1866, pi. XXXV, fig. 184.— "Hartman and Michener, Conch. Cest., 1874, p. 

 91, fig. 188.— *B. H. Wright, Check List, 1888.— * P.etel, Conch. Sam., Ill, 

 1890, p. 155. 



* Margarita ( Unio) heterodon. Lea, Syn., 1836, p. 18; 1838, p. 16. 

 ^Margaron ( Unio) heterodon Lea, Syn., 1852, p. 24; 1870, p. 36. 



Northern New England to Virginia. 



ALASMIDONTA DIVERSA Conrad. 



*Unio diversus Conrad, Am. Jl. Sci., XXI, 1856, p. 172 (fig. in outline). — B. H. 

 Wright, Check List, 



Alabama. 



(Grouj) of Alasmidonta collina.) 



Shell rhomboid, subsolid, with beak sculpture consisting of strong, 

 concentric bars, sometimes slightly doubly looped and swollen on the 

 low, posterior ridge; often with one or more small spines on the disk 

 in front of the posterior ridge; epidermis brown, rayless or feebly 

 rayed; rest marks well defined; teeth rather compressed; laterals 

 lamellar. 



Animal unknown. 



tALASMIDONTA COLLINA Conrad. 



*Unio collinus Coxrad, Monog., VIII, 1837, p. 65, pi. xxxvi, fig. 2; XII, 1840, 

 p. 109, pi. LX, fig. 3.—* Troschel, Arch, fiir Nat., IV, 1838, p. 287.— * Conrad, 

 Pr. Ac. N. Sci., Phila., VI, 1853, p. 247.— *Hanley, Biv. Shells, 1856, p. 382, 

 pi. XX, fig. 57.—" KuSTER, Conch. Cab. Unio, 1861, p. 188, pi. Lix, fig. 5.— 

 *SowERHY, Conch. Icon., XVI, 1866, pi. XLix, fig. 263.— *B. H. Wright, 

 Check List, 1888.—* P.«tel, Conch. Sam., Ill, 1890, p. 148. 



*Margaron {Unio) collinus Lea, Syn., 1852, p. 23; 1870, p. 35. 



North Carolina and Virginia. 

 ' Conrad says this has a remarkable resemblance to Unio heterodon, but is shorter. 



