32 THE NAUTILUS. 



The natural affinities of this species remain yet to be inves- 

 tigated. It seems to be a true Pleurobema, but represents, in 

 the shell, a peculiar type, which has no closer relation to any 

 of those, of which the soft parts are known. 



ELLIPTIC LANCEOLATUS (Lea) (See: Unio lane.., Simpson, 1900, 

 p. 734). 



I collected, on June 3, 1912, two specimens, one a gravid 

 female, in Mountain Run, Culpeper, Culpeper Co., Va., and 

 about a dozen, part of them gravid, on June 5, 1912, in Rapi- 

 dan River, Rapidan, Culpeper Co., Va. All gravid females 

 had eggs, and thus the beginning of the breeding season falls 

 probably in May. 



Structure of soft parts identical with that of E. complana- 

 tus, and chiefly with E. product us, agreeing with the latter in 

 the rather long mantle-connection between anal and supra- 

 anal (almost as long as anal). (See : Ortmann, 1812, p. 270.) 

 Structure of marsupium in the gravid female as described in 

 E. complanatus ; only the outer gills are marsupial, the eggs 

 are whitish, forming rather distinct, lanceolate and com- 

 pressed placentae. 



UNIOPICTORUM (Linnaeus) (See: Ortmann, 1912, p. 274). 



In 1911, I have received from W. Israel a number of gravid 

 specimens from Germany. They were collected on May 12, 

 15, 22, 27, and 28, 1911. Some of those collected on May 22, 

 27, and 28 had glochidia, and on May 22 some were in the act 

 of discharging. 



The investigation of the marsupium shows that the outer 

 gills are only moderately swollen, when charged, and that the 

 edge remains sharp and is not distended. The eggs form 

 lanceolate and compressed placentae, which are not very 

 solid, and when glochidia are developed, there is no or very 

 little cohesion between them; they fall easily apart and pass 

 out of the suprabranchial canals in loose, irregular masses. 

 No traces of lateral water canals have been observed, and the 

 ovisacs remain open below. 



The glochidia are of the Anodonta-type, as was known 



