138 C. ISHIKAWA. 



dorsal and ventral sides nearl}' of the same curvature ; the dorsal curve, 

 however, is not constant, changing with the contents of the breeding 

 chamber, i. e. being more curved in those females in which a great num- 

 ber of eggs or embryos are found than in those with only few of them. 

 The spine of the carapace is rather slender and its length is nearly one- 

 third that of the carapace. It is armed with four rows of sharp spinules 

 as usual the two upper continuing along the posterior third of the dorsal 

 edge of the carapace. The free inferior border of the carapace with the 

 exception of the most anterior part of it, is again beset with sharp 

 spinules the largest of which are found at about a third from the base of 

 the spine of the carapace, and diminish in size both anteriorly and 

 posteriorly just as in the Australian D. Lumholtzii, G. 0. Sars. The 

 most posterior part of the free border of the carapace, just in front of the 

 base of the spine, is again shghtly curved outwards, just as is observed 

 in the same part of the shell of the Europian Daphnia caudata. 



The matrix of the shell (Figs. 8 and 9) form two systems of delicate 

 striae running across each other and form, as usual, rhombic figures, the 

 meshes of which are smaller on the anterior part of the shell. At the 

 junctions of the striae are found star-shaped figures caused by the ends of 

 the pillars of connective tissue-fibres joining the two lamella of the 

 shell. 



The similar figures are seen also on the head of the animal, but the 

 network is of different forms, being more elongated on the most part of 

 the head, but are hexagonal near the rostrum. 



The shell-gland (Fig. 5) is well developed. It is of an usual S- 

 shaped figure commencing with a narrow entrance-canal and ending 

 in an enlarged terminal chamber. The glandular portion of the organ 

 is well developed, its large cells are well seen even with a low magnifica- 

 tion. 



Viewed from the dorsal side (Fig. 2), the carapace presents an 

 elongated ovum whose anteiior end becoming narrower than the posteri- 

 or in those females in which a great number of eggs or embryos are 

 found in the breedinji chamber. 



