On Fresh-Avater Entomostraca. 13 



Description of the female. 



The length of the largest specimens examined is about 

 3 mm., and this form accordingly grows to a rather large 

 size, as compared with the other species of the genus. 



The shell, as in the other species, is rather tumid, and 

 somewhat navicular in shape. Seen laterally (fig. 1), it ex- 

 hibits an irregular oval, or oblong sub-rhomboidal form, with 

 the posterior extremity remarkably produced, and forming 

 a rather large, obtusely conical prominence extending some- 

 what above the longitudinal axis of the body. The pro- 

 mineuce is not defined above by any distinct sinus, and 

 exhibits at the tip a number of small appressed denticles. 

 The dorsal margin of the shell is quite evenly convex 

 throughout, and continuous with that of the head, though, 

 as usual, a small indentation may be traced between the two 

 in the cervical region. The inferior edges of the valves are 

 greatly bulging in front, and posteriorly join the obliquely 

 ascending posterior edges by an even curve. 



The head (see also fig. 2) is comparatively small and 

 procumbent, and is highly distinctive by the production of 

 the front into a very conspicuous acute, deflexed projection, 

 resembling a rostrum. Behind the latter, the ventral edge 

 ascends obliquely and quite evenly to the small, deflexed, 

 true rostrum. The fornix is moderately prominent, and of 

 the usual appearance, joining the valvular part of the shell 

 at a very acute angle. 



The shell is sculptured in the usual manner by oblique, 

 partly anastomosing striæ, running parallel to the posterior 

 edges ; and exhibits inside, at some distance from the inferior 

 edges, a ciliated ridge. 



