Ortmann; Families and Genera of Najades. 333 



with crenulations, but without papillae. Marsupium kidney-shaped, 

 swollen, consisting of many ovisacs, occupying the posterior part of 

 the outer gill. Placentae not very solid. Glochidia rather large, 

 celt-shaped, with two spines, one at each of the ventral corners. 



Type P. alata (Say). 



This genus stands in all characters except the glochidia, by the side 

 of Paraptcra. The shape of the glochidia is unique. 61 



Proptera alata (Say). 



About a dozen specimens from the Ohio and Lake Erie in western 

 Pennsylvania have been studied, and a gravid female from the Kansas 

 River in Kansas (R. L. Moodie). 



The breeding season begins unusually early, eggs having been found 

 in the marsupium on June 22. Glochidia have been seen in July, 

 August, September, and October, and then again in May. This refers 

 to specimens from the Ohio drainage. In Lake Erie, specimens with 

 glochidia have been found in May, and discharging specimens as late 

 as July 7 and 8. The beginning of the breeding season in Lake Erie 

 has not been observed. Thus the end of one and the beginning of 

 another breeding season seem to overlap, of course not in the same 

 individual, and probably not in the same locality. 



The soft parts have been described by Lea (Obs., X, 1 863, p. 403) 

 and Simpson (in Baker, 1898, p. 98). 



It is hardly necessary to describe the anatomy in detail, since it 

 agrees in every respect with that of Paraptera gracilis, with the ex- 

 ception of the mantle-connection between anal and supra-anal, which 

 is here slightly shorter, and the glochidia. The latter (see Lea, Obs., 

 VI, 1858, i>l. 5, fig. 25; Lefevre and Curtis, 1910, p. 97, fig. D, and pi. 4, 

 fig. 25; Ortmann, 191 16, pi. 89, fig. 18; and Coker and Surber, 1911, 

 pi. 1, fig. 3) are so fundamentally different, that the creation of the 

 genus Proptera is justified. Their dimensions are, according to Le- 

 fevre and Curtis: length 0.23; height 0.41. The specimens measured 

 by me were not so large, being in length 0.20; height 0.38 mm. 



51 According to Coker and Surber (1911), Lampsilis capax (Green) has the glo- 

 chidium similar to that of the species of Proptera. It should be ascertained whether 

 the margin of the mantle of this species is that of Lampsilis or that of Proptera, 

 before we assign it to Proptera. 



