THE NAUTILUS. 



63 



nated by L. S. Frierson and collected by A. A. Hinkley on 

 July 30 and Aug. 2 and 5, '14, A number of specimens (8) 

 were preserved in alcohol, coll. July 30 and Aug 2, which all 

 were gravid females, and one of each date had glochidia. This 

 marks probably the end of the breeding season, and the species 

 is tachytictic. 



There is some confusion with regard to this species. After 

 the first description by Call, it has not again been recorded, ex- 

 cept by Meek and Clark, and I believe, the identification of 

 these authors (supported by B. Walker) is correct. But I think 

 that other authors have seen this form, but have not recognized 

 it, and, for instance, Simpson's pannosus and subellipticus (re- 

 garded as varieties of Pleurobema argenteum and breve respec- 

 tively) are also this. Frierson' s utterbacki is surely this, since 

 my specimens were thus labeled by Frierson. 



Walker, Frierson, and Simpson (in part) believe this to be a 

 Pleurobema, and not a Lampsilis (see also Simpson, '00, p. 557, 

 and '14, p. 131), and this comes nearest to the truth, in fact, 

 it is the most plausible assumption to be made from the study 

 of the shell alone. The shell "resembles a very elongated 

 Quadrula coccinea," according to Meek and Clark, and the com- 

 parison with Pleurobema argenteum and breve (which, by the 

 way, are synonyms), made by Simpson, is significant. We 

 must keep in mind that Call's fig. 4 represents the normal shape 

 of the shell, while his fig. 1 is rather abnormal, and possibly 

 does not belong here at all. These two figures by no means 

 represent the female and male, as Call believes. 



The investigation of the soft parts has shown that this actually 

 is a Fusconaia. Corresponding, both in soft parts and shell, to 

 the barnesiana-ty-pe of the upper Tennessee region. F. ozarkensw 

 differs from barnesiana by the more elongated (subtrapezoidal) 

 outline of the shell, more anterior beaks, and the weak devel- 

 opment of the rays, which are faint at the best, and often en- 

 tirely absent. A swollen form of it is not known to me, but 

 specimens from White River are slightly more convex than 

 those from James River (farther up). Also Utterback's quota- 

 of Frierson (p. 87, footnote) make it probable that there are 

 differences in obesity. 



