6 G. 0. Sårs. 



however, for the certain identification of this form with the 

 one here described. It is a very beautiful species, and, at 

 least in the male sex, at once recognizable from any of the 

 other species known. 



Description. — The length of adult ovigerous female 

 specimens, measured from the front to the tip of the caudal 

 rami, is about 18 mm., that of male specimens is consider- 

 ably greater, amounting to 22 mm. 



The general form of the body (see figs. 1 & 2), as com- 

 pared with that in other species of this genus, appears some- 

 what robust, especially in the female, the posterior division 

 not being very slender, and scarcely exceeding in length the 

 anterior division. The proportions of the several sections 

 of the body are, however, somewhat different in the two 

 sexes. These sections are as follows: head, cervical seg- 

 ment, trunk, genital region and tail proper, the last 2 sections 

 belonging to the posterior division, the remaining 3 to the 

 anterior. 



The head is well defined behind in both sexes by the 

 cervical depression, immediately beneath which the mandibles 

 are visible. In the female (fig. 1) it is evenly rounded in 

 front, and comparatively smaller than in the male. In the 

 latter (fig. 2) the front is produced to a short conical pro- 

 tuberance (fig. 3), which, however, in the lateral view of the 

 animal is concealed by the base of the antennæ. 



The cervical segment in both sexes is about half the 

 length of the head, and evenly convex above. Below on 

 each side, it forms a projecting, narrowly rounded lobe con- 

 taining the shell-gland, and more properly constituting a 

 slight rudiment of the shell or carapace so strongly developed 

 in the other 2 divisions of Phyllopoda, the Noiostraca and 

 Conchostraca. 



