On Fresh-water Entornostraca. 



b. Var. intermedia. 



(Fig. 3). 



In this variety, which is of somewhat smaller size, mea- 

 suring in length, without the spine, 3,35 mm., the head appears 

 comparatively larger in proportion to the shell, with the 

 dorsal crest more developed. The shell is less narrowed 

 posteriorly, and the spine issues considerably above the 

 longitudinal axis, being obliquely upturned. 



All the specimens of this variety, which I have had 

 an opportunity of examining, were provided with ephippia, 

 and accordingly belonged to the later generations. 



The ephippium is rather narrow and, seen laterally, of 

 a somewhat fusiform outline, with the anterior extremity 

 prolonged into a narrow stripe extending along the cervical 

 part of the shell and, like the whole dorsal margin, densely 

 denticulated. The egg-ampullæ are rather small and obliquely 

 disposed, exhibiting a very dark hue, whereas the remaining 

 part of the ephippium is opaque whitish. 



c. Var. magniceps. 



(Fig. 4). 



This variety, which attains a length, without the spine, 

 of 3V2 mm., differs considerably in its outward appearance 

 from the two preceding ones, though evidently belonging to 

 the same species. The shell is comparatively shorter and 

 broader, and exhibits a rounded quadrangular form, with 

 the dorsal margin nearly straight, and not defined from the 

 head by any perceptible sinus. The spine, which issues 

 far above the longitudinal axis, is considerably upturned, and 

 about half the length of the shell. The head is exceedingly 



