Fresh- water Entomostraca of South America. 13 



As usual, the generations at first appearing were all 

 parthenogenetic, and in comparatively short time multiplied 

 very abundantly, the matrix of the individuals being often 

 found i;o be greatly distended with young. But at the close 

 of the season the fertility considerably diminished, and soon 

 the opaque contents of the ovaria, in connection with 

 the somewhat darkened upper part of the carapace, clearly 

 indicated that the individuals were now about to produce 

 the so-called winter-eggs or resting ova. Never more than 

 2 of these, are found in each individual, and they are 

 always located side by side in the anterior part of the 

 matrix, exhibiting very distinctly the above-mentioned peculiar 

 scabrous appearance (see fig. 2). At the same time also 

 male specimens appeared rather frequently, and were often 

 seen in ardent pursuit of the females. 



Occurrence. — The aquaria in which this form 

 developed, were all prepared with mud taken in the im- 

 mediate neighbourhood of Sâo Paulo. 



Distribution. — The specimens examined by Mr. 

 Richard were found, together with another species, in a 

 sample of plankton taken in Lake Toba, Sumatra. The same 

 species has recently been recorded by Mr. v. Daday from 

 the German dominion of New Guinea. The distribution of 

 the present species accordingly extends through the tropical 

 part of 3 different continents. 



3. Diaphanosoma brevireme, n. sp. 



(PI. II, figs 11—16). 

 Specific Characters. — Female. Form of 

 carapace about as in the preceding species, its upper part, 

 however, being sometimes distended in quite an extraordi- 



