﻿47^ .\kciiii:.\s 



a number of radiatinj^", wavy, sul)nu(lulous lir^c or small ridges; 

 from the anterior row of knobs extending backwards and 

 downwards there is a series of strong folds and these are 

 crossed by wrinkled, radiating, sometimes zigzagged, threads ; 

 the posterior slope has radial, wrinkled sculpture, while the an- 

 terior base has usually merely concentric stritC ; posterior ridge 

 rather high ; post-dorsal region almost winged ; epidermis 

 brownish-green with dark l^ands, sometimes clouded ; left valve 

 with an arched, somewhat elongated tooth un<ler the beak, 

 which often curves upward ; in front of this there is a com- 

 ])rcssed tooth ; right valve with a strong, subcompressed tooth 

 in front of the bccik ; at the beak the hinge plate is cut away 

 for the reception of the tooth in the left valve; laterals reduced 

 to blurred, uneven vestiges ; beak cavities deep ; muscle scars 

 shallow; nacre bluish-white, dull, often with uneven radial 

 sculpture, wnth a wide prismatic border. 



Length TOO, height 75, diam. 48 mm. 



Mississippi River and states adjoining it; Ohio Fviver drain- 

 age ; southwest to Colorado River. Texas ; P)ayou Teche. Lou- 

 isiana : ? Enterprise, southeastern Alabama. 



Type locality. New Orleans, La. 

 Alasmodonta conjragosa Sav, N. Harm. Diss , II, 1829, p. 339; 



Am. Conch., I, 1830, pi. xxi. — Chenu, Bib. Conch., ist ser.. 



Ill, 1845, p. 30, pi. VIII, figs. I, \a. 

 Margarita (Margaritana) confragosa Lea, Syn., 1836, p. 43 ; 



1838, p. 27. 

 Unio confragosa Deshayes, An. sans Vert., 2d ed.. \'I, 1835, 



p. 552. — Hanley. Biv. Shells. 1843. p. 210, pi. xxiii. fig. ^2. 



— Desh.vyes, Tr. Elem.. 1853. p. 217. pi. xxx, figs. 5-7. 

 Baphia confragosa II. and A. .Adams. Gen. Rec. Moll., IT, 



T857. p. 500. 

 Margaron (Margaritana) confragosa Lea, Syn., 1852, ]). 42; 



1870, p. 67. 

 Margaritana confragosa Cai.kins, Pr. Ottawa Acad.. 1874, 



p. 46. 

 Unio confragosns Sowkrhy, Conch. Icon.. X\'T. 1867. ]il. i.x. 



fig. 299. 



