1885.] 



CLADOCERA. 



27 



carapace by a rather deep dorsal impression. Its dorsal margin 

 is rather convex in the upper part, but farther down forms a 

 s light concavity above the eye. The frontal part projects a 

 little inferiorly, jutting out as two acute processes, that point 

 in opposite directions. The posterior and larger process repre- 

 sents a kind of rostrum, projectiDg in front of the antennulæ; 

 the anterior, which issues from the foremost part of the front, 

 has the form of a small cornicle, pointing straight forward, muen 

 as in the cornigerous variety of our common Scapholeberis mu- 

 cronata. The fornix would appear to project a little above the 

 bases of the antennæ, and is there produced on either side as a 

 short triangular lappet. 



The carapace — lateral aspect — exhibits a comparatively 

 regular, broadly oval shape, both with the upper and lower mar- 

 gins gently arched, and the posterior part, a little above the 

 middle, produced as a short spiniform process, that, on viewing 

 the animal from above, appears bifurcate, or to jut forth with 

 two acute and diverging points (see fig. 2). 



The sculpture of the carapace, as also of the cephalic shell, 

 is very distinct, forming over the whole surface a net-work of most 

 conspicuous polygonal meshes, those on the valves occurring larger 

 and more regular in form than elsewhere. The free edges of the 

 valves are quite smooth, without any trace of bristle? or denticles. 



The eye is of moderate size, and, as usual, placed within 

 the frontal region of the head, not by far, however, filling up that 

 part. The ocular spot is distinctly visible, though very minute, 

 punctiform, and placed at a short distance from the insertion of 

 the antennulæ. 



The antennulæ are rather small, not reaching by far to the 

 tip of the rostral projection, and well-nigh fusiform in shape, 

 having the tentacular seta affixed about in the middle of the 

 anterior margin. 



The antennæ appear somewhat less powerfully developed 

 than in most of the other species, and with the outer branch 

 considerably shorter than the inner; for the rest exhibiting the 

 usual structure. 



