﻿506 .\I..\S.M11H)NTA 



refiexed. T have seen old. solid shells, which seemed to iiavc 

 a raylcss. nearly black or brown epidermis, but when held up 

 to the li,i;lil the rays could be seen. 



Al.asmii)OiNTa VAUicosA (Lamarck). 



Shell of medium size, thin, long rhomiboid, with moderately 

 full, slightly elevated beaks, their sculpture consisting of heavy- 

 ridges that run nearly parallel to the growth lines ; posterior 

 ridge high, generally double, ending in a biangulation near 

 the base of the shelC the greatest inflation being along this 

 ridge ; posterior slope slightly corrugated, remainder of the 

 surface irregularly marked with growth striae; epidermis dirty 

 yellowish-green with feeble, sometimes clouded, rays ; left 

 valv^e with a faint tooth under or a little in front of the beak ; 

 right valve with an anterior tooth ; laterals wanting ; nacre 

 bluish, lurid in the cavities with a distinct, narrow prismatic 

 border. 



Length 54, height 2,2, diam. 20 mm. 



Lower St. Lawrence ; southward in streams draining into 

 the Atlantic to South Carolina. 



Type locality, Schuylkill River near I*hiladcli)hia, Pa. 

 Unio 7-aricosa Lam.vkck, An. sans \'ert., VL 1819, p. 78. 

 Alasmidonta mari^inata Simi'.son, S\n.. kjcx). \). 670. 

 Alasmodon mari^^inata Gould, Inv. Mass., 1841, p. 116, fig. yj. 



— De Kay, Zool. of X. Y., Pt. v. 1843, P- 196. pk xiv, fig- 



Unio mar^^inata Hanlky, Biv. Shells, 1843, p. 211, pi. xxi, fig. 



.Inodonta luanjiiiato C. ?>. Adams, Thompson's Hist., 1842. p. 



164. 

 Baphia mari^iiiata TL and A. .\l)A^rs. Gen. Rec. Moll.. TL 1857, 



p. 500. 

 Mar»;aritaiia inariiijiata Goui.d, Tnv. of Mass., 1870, p. 177, 



fig. 479. — Haktmax and Miciiener, Conch. Cest., 1874, p. 



93, fig. T91. 

 Unio marg^inatus Cati.ow and Reicvk. Conch. Nom., T845, p. 



6t. 

 Unio cariosa T^amarck, .An. sans \'ert.. YJ, 1819, p. 80. 



