NO. 1205. SYNOPSIS OF THE NAIADES— SIMPSON. 665 



Animal witli the marsupium occupying tbe whole of the outer gills, 

 very thick, like that of Anodonta; inner gills free all or the greater part 

 of their length from the abdominal sac; branchial opening papillose; 

 anal opening generally smooth or only slightly creuulate. * 



tSYMPHYNOTA COSTATA Rafinesque. 



*Alasmidon1a costaia Rafinesque, Ann. Gen. Sci. Brnx., V, 1820, p. 313, pi. 



Lxxxii, figs. 15, 16. 

 *Alasmodonia costaia Say, Am. Conch., VI, 1834.—* Conrad, New F. W. Shells, 



1834, p. 72.—* Feiu'SSac, Guer. Mag., 1835, p. 25 

 *CompIanaria costaia Coxkad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 261. 

 *Alasmodonta rugosa Barnes, Am. Jl. Sci., VI, 1823, p. 278, pi. xiii, fig. 21.— 



Short and Eaton, Transylvania JL, 1831, p. 81. — * C. B. Adams, Thompson's 



Hist, of Vt., 1842,p. 165.— * Baker, Moll. Chicago, Pt. 1, 1898, p. 57, pi. vii, 



figs. 1,2; VIII, figs. 3,4. 

 *Mya rugosa Eaton, Zool. Text-Book, 1826, p. 222. 

 ^Margarita {Margaritana) rugosa Lea, Syn., 1836, p. 44; 1838, p. 27. 



* Unio rugosa Hanley, Test. Moll., 1842, p. 211 ; * Biv. Shells, 1843, p. 211, pi. xxi, 



tig. 8. 

 ""Alasmodon rugosa De Kay, Zool. N. Y., Pt. 5, 1843, p. 196, pi. xiv, fig. 226. 

 *Complanaria rugosa Stimpson, Sheils of N. Eng., 1851, p. 14. 

 Margaron {Margaritana) rugosa Lea, Syn., 1852, p. 42; 1870, p. 67. 



* Baphia rugosa H. and A. Adams, Gen. Rec. Moll., II, 1857, p. 500. 



* Margaritana ruqosa Calkins, Pr. Ottawa Ac. Sci., 1874, p. 46. — * B. H.-Wright, 



Check List, 1888.—* P^tel, Conch. Sam., Ill, 1890, p. 164. 



* Lasmigona rugosnm Rafinesqui^, Cont. Mon., Og,, 1831, p. 5. 



* Unio rugosus Catlow and Reeve, Conch. Nom., 1845, p. 63. — Kuster, Conch. 



Cab. Unio, 1861, p. 200, pi. lxvi, figs. 1-3.— Sowerby, Conch. Icon., XVI, 1867, 

 pi. LX, fig. 302. 

 ^Alasmodonta Mans Ferussac, Guer. Mag., 1835, p. 25. 



Mississippi drainage generally; St. Lawrence basin ; Manitoba; Hud- 

 son Eiver*?; Columbus, Mississippi. Texas 1 



Subgenus PTEROSYGNA Eaflnesque, 1831. 

 (Type, Alasmodonta complanata Barnes.) 



Shell large, ovate-rhomboid, inflated in post basal region ; beaks much 

 compressed, their sculpture sharply and strongly doubly looped; epi- 

 dermis dark, scarcely rayed; teeth very heavy. 



Animal with an extremely thick marsupium; palpi large; mantle with 

 small crenulations on lower border; branchial opening large; anal open- 

 ing small, both slightly papillose. 



tSYMPHYNOTA COMPLANATA Barnes. 



* Alasmodonta complanata Barnes, Am. .11. Sci., VI, 1823, p. 278, pi. xiii, fig. 21.— 



*Hildreth, Am. Jl. Sci., XIV, 1828, p. 289.— * Conrad, NewF.W. Shells, 



1834, p. 72.—* Say, Am. Conch,, VI, 1834.—* Baker, Moll. Chicago, Pt. 1, 1898, 



p. 60, pi. viii, figs. 1, 2 ; IX, figs. 1-4. 

 ''My a complanata Eaton, Zool. Text-Book, 1826, p. 222. 

 *Symphgnota complanata Lea, Tr. Am. Phil. Soc, III, 1830, p. 448. — * Short and 



Eaton, Transylvania JL, 1831, p. 80.—* Lea, Obs., I, 1834, p. 62.— Ferussac, 



Guer. Mag., 1835, p. 25. 



