NO 1205. STXOPSIS OF TH E XAI AD ESSI MFSOX. 669 



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

 face rayed; pseudocardiuals compressed, reflexed; laterals single, 

 double, or triple iu each valve. 



Animal with branchial opening having a few coarse papilla; anal 

 opening smooth, or with very fine crenulations. 



fALASMIDONTA HETERODON Lea. 



* Unio heterodon LEA, Tr. Am. Phil. Soc., Ill, 1830, p. 428, pi. vin, fig. 11 ; * Obs , I, 



1834, p. 42, pi. vin, tig. 11. * CONRAD, New F. W. Shells, 1834, p. 69. 



* FERUSSAC, Guer. Mag., 1835, p. 26. * DESHAYES, An. sans Vert., 2cl ed., VI, 



1835, p. 548; 3d ed., II, 1839, p. 672. * CONRAD, Monog., X, 1838, p. 90, pi. 

 XLIX, tig. 3. *HANLEY, Test. Moll., 1842, p. 183; Biv. Shells, 1843, p. 183, 

 pi. xxi, tig. 42. * CATLOW and REEVE, Conch. Nom., 1845, p. 59. * CONRAD, 

 Pr. Ac. N. Sci., Phila., VI, 1853, p. 250.* CHENU, 111. Conch., 1858, pi. xvi, 

 ligs. 2, 2a, 26.* H. and A. ADAMS, Gen. Rec. Moll., If, 1857, p. 495. *Kus- 

 TER, Conch. Cab., 1861, p. 192, pi. LXI, tig. 2. * SOWERBY, Conch. Icon., XVI, 

 1866, pi. xxxv, fig. 184. *HARTMAN and MICHEXKR, Conch. Cest., 1874, p. 

 91, tig. 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. 

 *3far(/aron ( Unio) heterodon LEA, Syii., 1852, p. 24; 1870, p. 36. 



Northern New England to Virginia. 



ALASMIDONTA DIVERSA Conrad. 



*Unio diversm CONRAD, Am. Jl. Sci., XXI, 1856, p. 172 (fig. in outline). B. H. 

 WRIGHT, Check List, 1888.' 



Alabama. 



(Group 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 

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

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

 lamellar. 



Animal unknown. 



t ALASMIDONTA COLLINA Conrad. 



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

 p. 109, pi. LX, fig. 3.* TROSCHEL, Arch, fur Nat,, IV, 1838, p. 287.* COXRAD, 

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

 pi. xx, fig. 57.* KUSTER, Couch. Cab. Unio, 1861, p. 188, pi. LIX, fig. 5. 



* SOWERBY, Conch. Icon., XVI, 1866, pi. XLIX, tig. 263. * B. H. WRIGHT, 

 Check List, 1888. * PJETEL, Conch. Sam., Ill, 1890, p. 148. 



* Margaron (Unio) collinus LEA, Syn., 1852, p. 23; 1870, p. 35. 



North Carolina and Virginia. 



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



