﻿44 I.AMI'SII.IS 



crc bluish-while, much thinner behind. The female shell has 



a well-developed marsujiial swelling and is j^enerally shorter 



and higher than that of the male. 



Length 120, height 80. diam. 45 mm. 



Length 105. height 63, diam. 35 mm. 



Atlantic drainage from Georgia to the lower St. Lawrence. 



Type locality, Delaware and Schuylkill Rivers. 



Unio cariosus Say, Nich. Encyc, II, 1817, pi. ni, fig. 2. — Con- 

 rad, Monog., IV, 1836, p. 40, pi. XIX. — Gould, Inv. of 

 Mass., 1841, p. Ill, fig. 72; ]3inney. Inv. of Mass., 1870, 

 p. 172, fig. 475. — Rekve, Condi. Syst., T, 1841, p. 119, pi 

 Lxxxix. fig. 10. — Df, Kay, Zool. of N. Y., Pt. 5, 1843, p 

 193, pi. XXI, figs. 243, 244. — Hanuey, Biv. Shells, 1843, p 

 190. pi. XX, fig. 22. — ^KusTER, Conch. Cab. Unio, 1852, p 

 24, p'l. I, figs. 2, 3. — SowERBY, Conch. Icon., XVI, 1867, pi 

 LViii, fig. 294. — Hartman and Miciiener. Conch. Cest., 

 1874, p. 38, fig. 183. — Simpson, Naut., \\U, 1895, p. 122, 

 2 figures. 



Margarita (Unio) cariosus Lea, Syn., 1836. p. 23; 1838, p. 18. 



Margaron (Unio) cariosus h'E a, Syn., 1852, p. 27; 1870, p. 42. 



Lampsilis cariosus Simpson, Syn., 1890. p. 528. 



Unio cariosa Lamarck, An. sans Vert., VI, 1819, p. 80. 



Mya cariosa Eaton, Zool. Text-Book, 1826, p. 218. 



Lampsilis cariosa Stimson, Shells of N. Eng., 1851, p. 14. 



Unio ovatus var. b. Lamarck, An. sans \'ert., \], 1819, p. 75. 



Unio ovata Vaixnciennes, Rec. Obs. Zool. Anat., II, 1833, p. 

 226, pi. L, figs. I, I a, i&, ir. 



Unio viridis Ferussac, Guer. Mag., 1835, p. 2y. 



Unio oratus Conrad. Ann. and Mag. Nat. Hist., IV, 1849, p. 

 301 ; Jl. Ac. N. Sci. Phila., 1850, p. 276. pi. xxxvii, fig. 6. 

 This species has frequently been confounded with L. ochra- 



cea Say, with which it is generally associated, but which is 



really a very different species. It is nearer to L. ventricosa, 



but is always smaller and more delicate in ever}' way, more 



compresse<l and is seldom rayed except on the posterior slope. 

 The specimens referred to this species that are often report- 

 ed from the Mississippi drainage are no doubt /,. 7'cntricosa. 



