Ortmann: Families and Genera of Najadi -. 331 



Paraptera gracilis (Barnes). 17 



I myself collected about a dozen specimens with soft parts in the 

 Ohio and Lake Erie in western Pennsylvania, and received, from R. L. 

 Moodie, a male from the Kansas River in Kansas, and from L. S. 

 Frierson a male and a sterile female from Bayou Pierre, Louisiana. 



The breeding season seems to have certain peculiarities. The 

 species is undoubtedly bradytictic, but the season begins rather late. 

 I found specimens with the marsupium partly charged as early as 

 August 30, but these, as well as others found in September and October, 

 all had only eggs, but no glochidia. In spring, a discharging female 

 has been observed as early as May 22, but others were found fully- 

 charged with glochidia as late as July 7, 8, and n. 48 Thus the breeding 

 season must last from the end of August to about the middle of July, 

 with only a very short interval. 



Incomplete descriptions of the soft parts have been published by 

 Lea (Obs., X, 1863, p. 434) and Simpson (in Baker, 189S, p. 99). 



Anal and supra-anal separated by a mantle-connection which is 

 slightly longer than the anal. Anal crenulated, branchial with papillae. 

 In the female the inner edge of the mantle in front of the branchial 

 is lamellar, somewhat dilated, with fine crenulations, running forward 

 for about one-third the length of the margin of the mantle. No 

 papillae are present. Palpi with the posterior margins united at the 

 base on'y. 



Gills and diaphragm of normal shape. Inner lamina of inner gills 

 connected throughout with abdominal sac. Structure of gills normal. 

 Marsupium formed by the posterior part of the outer gill, kidney- 

 shaped, and swollen. Ovisacs numerous (thirty to forty), lanceolate. 

 Placentae not very solid, glochidia distributed all through the mass, 

 very small, of suboval shape. Length 0.08; height 0.09 mm. (See 



47 Lea (Obs., VIII, 1862, p. 79, pi. 9, fig. 224) described U. dolosus, which Simpson 

 (1900&, p. 568) makes a synonym of U. purpuralus Lea, but states that the glochidia 

 are pouch-shaped (Lampsilis-type), not wedge-shaped as in Paraptera purpurata. 

 Simpson dismisses this by saying (I. c, footnote 2) that the "form of embryos in a 

 given species is often not constant." This is a very serious mistake, for there is 

 nothing more constant for the species than the glochidium. Call (1895, p. 19) 

 makes dolosus a synonym of gracilis, and I think that he is right. Simpson (I. c, 

 p. 574) does not report gracilis from the Alabama drainage, but it surely is there 

 (as dolosus). I have myself seen two specimens from the Coosa River at Wetumpka, 

 collected by H. H. Smith in October, 1901. 



48 Those collected July 7 and 8 are from Lake Erie, but the one collected July 1 1 

 is from the Ohio River. 



