310 



Annals of the Carnegie Museum. 



marsupium to a few ovisacs, compensating for the reduction in their 

 number, by an increase in their length. The tendency to move the 

 marsupium backward toward the branchial opening is but slightly 

 indicated. 



Obliquaria reflexa Rafinesque. 



Three males and one sterile female from the Ohio in Beaver Co., 

 Pennsylvania, and another sterile female taken at Portsmouth, Scioto 

 Co., Ohio, have been collected by myself. I received a sterile female 

 from the Ouachita River, Arkadelphia, Clark Co., Arkansas, collected 

 by H. E. Wheeler, February 6, 191 1; and two males and four gravid 

 females from Bayou Pierre, De Soto Parish, Louisiana, collected by 

 L. S. Frierson, August 6, 1910. 



Soft parts described by Lea (Obs., X, 1863, p. 429) and figured by 

 Lefevre and Curtis (1910, pi. 1, fig. 3). 



Branchial, anal, and supra-anal 

 as usual, mantle connection be- 

 tween the two latter moderately 

 long, but shorter than the small 

 anal. Branchial with papillae, anal 

 crenulated. Toward the front the 

 papillae of the branchial disappear 

 suddenly, and the edge of the 

 mantle is smooth, with a few indis- 

 tinct crenulations just in front of 

 the branchial. Palpi normal, their 

 posterior margins connected only 

 at bate. 



Gills short and broad, the inner 

 wider anteriorly. Diaphragm normal; inner lamina of inner gills free 

 from abdominal sac except at anterior end, where a portion less than 

 half the length of the abdominal sac is connected. Anterior ends of 

 gills normal. 



Septa and water-tubes of both gills of the usual structure in the 

 male. In the female, the marsupium is formed by a part of the outer 

 gill lying just behind the middle of the gill, and not extending to the 

 posterior end of it. The most characteristic feature is that the mar- 

 supium consists only of a small number (four to six in my specimens, 

 but reported up to eight) of ovisacs, which, when empty, are hardly 



Fig. 16. Obliquaria reflexa Rafin- 

 esque. Gravid female, from Bayou 

 Pierre, De Soto Parish, La. 

 Mus., No. 61, 4.755-) 



(Cam. 



