﻿STROPiriTus 349 



Strophitiis cdeiitiilus var. pavonius Simpson', Syn., 1900, p. 617. 

 Anodon annulatus Sowerby, Conch. Icon., XVII, 1867, pi. 



XVIII, fig. 67. 



An almost infinitely variable species as to size, solidity and 

 form. Specimens from Tennessee are decidedly rhomboid, 

 rather compressed, and light brown-colored, others from the 

 vSt. Lawrence drainage are quite small and reddish or lurid 

 brown. One of these from the Maumee basin, which seems 

 to be mature, measures 35 millimeters long, 20 high, and 12 

 in diameter. Some of the old shells become very solid, other 

 forms are thin and fragile. The form I have called variety 

 pavonius is hardly worth a separate name, as there is a great 

 deal of material varying all the way from rayless to brightly 

 rayed. 



Strophitus unduuatus (Say). 



Shell generally subrhomboid, scarcely inflated, rather thin, 

 inequilateral, with high beaks, whose sculpture consists of a 

 few very strong ridges running parallel witii the growth lines, 

 turning up somewhat behind ; behind these there are usually 

 a few radial lir?e ; posterior ridge generally well developed and 

 angular, sometimes double ; surface with fine growth lines ; 

 epidermis dull ashy, ashy-green or smoky, often with faint, 

 darker rays ; hinge line narrow, somewhat incurved in front 

 of the beak, having the merest vestiges of pseudocardinals and 

 no laterals; beak cavities not deep; nacre bluish, often straw- 

 colored, buff or pale salmon in the shell cavities. 



Length 63, height i^y, diam. 2t^ mm. 



Length 30, height 20, diam. 12 mm. 



Northern New England to Virginia, in streams draining 

 into the Atlantic. This species is reported from Manitoba, but 

 it is probable that the specimens from that region are S. eden- 

 tiilus. 



Type locality not given. 

 Anodonta iindulata Say, Nich. Enc, II, 1817, -pi. iii, fig. 5. 

 Margarita (Anodonta) undulata Lea, Syn., 1836, p. 50; 1838, 



p. 30. 



