270 Annals of the Carnegie Museum. 



Elliptic* jayensis (Lea). 



Five males and twelve females (all sterile) from Lake Monroe, 

 Sanford, Orange Co., Florida, collected by O. T. Cruikshank, in 

 April, 1907. 



The soft parts are of the usual structure, and agree in every particular 

 with those of E. complanatus. Anal and supra-anal separated by a 

 mantle-connection, which is slightly longer than in the more primitive 

 forms, but still considerably shorter than the anal. Anal with rather 

 well developed papillae, which are almost as large as the papillae of the 

 branchial opening. Posterior margins of palpi connected at base only. 

 Inner lamina of inner gill free, except at anterior end. Only the outer 

 gills are marsupial. 



The beak-sculpture of this species is net quite of the normal Elliptio- 

 type, in that in the case of the later bars a sinuation is seen in front 

 of the posterior angle. This sinuation is variable, and never assumes 

 the shape of a distinct, reentering angle, and thus the beak-sculpture 

 cannot be called double-looped. 



There are over one hundred shells (without the soft parts) at hand, 

 many of which might as well be called E. buckleyi (Lea). All these 

 shells undoubtedly are the same species, and were collected together. 



The old ones most resemble buckleyi (see: Simpson, 1892, pi. 58, 

 figs. 6 and 7, and pi. 59, fig. 1), while those of medium size and the 

 young ones are jayensis (Simpson, ibid., pi. 61, fig. 4). It is remarkable 

 that there are no young buckleyi in the lot, while there are dozens of 

 jayensis. I am very much inclined to regard buckleyi as being only 

 the older adult form of jayensis. 



Elliptio productus (Conrad). 



Nine specimens have been investigated, males and sterile females, 

 from the Potomac drainage in southern Pennsylvania and Maryland. 



The soft parts agree in all essential respects with those of E. com- 

 planatus. Conforming to the shape of the shell, the gills are extremely 

 long and narrow. Branchial, anal, and supra-anal as in complanatus; 

 anal and supra-anal separation slightly longer than usual; anal with 

 the same distinct papillae. Structure of palpi and gills the same. 

 No gravid females have been found. 



Color of soft parts like that of complanatus. 



Beak sculpture practically identical, and there is no doubt that this 

 species is an offshoot of the complanatus-stock. 



