Fresh-water Entomostraca of South America. 41 



rather quickly through the water with rhythmical strokes of 

 the antennæ, though the motion was effected in a somewhat 

 clumsy manner. In the structure of the caudal part, as also 

 in several other points, this form likewise very much resem- 

 bles the North American species, I. spinifer Herrick, which, 

 however, is said to have the setæ of the antennæ quite 

 short, as in the Ceylon form. It may be here observed 

 that the number of curved spines in the lateral rows of the 

 tail is subject to considerable variation with age, only 3 

 or 4 such spines being counted on each side in young 

 specimens, whereas their number in adult specimens may 

 increase to 6 or 7 on each side. In the Australian speci- 

 men figured in the above-mentioned paper, their number was 

 no less than 8 on each side; but this specimen was a very 

 old one, as shown by the great number of lines of growth 

 on the carapace. 



Detached ephippia of the present form were often found 

 in the bottom residue of my aquaria. They are (see fig. 9) 

 easily recognizable by their very broad quadrangular form 

 and great pellucidity, the central part being coarsely sculp- 

 tured and containing 2 comparatively small resting eggs. 



The peculiar structure o£ the legs in this genus is 

 demonstrated by the figures 4 — 8 on the accompanying 

 plate, representing a leg of each pair from the present 

 species. 



Occurrence. — The aquaria in which this form 

 developed, were prepared with mud partly from Sâo Paulo ? 

 partly from Itatiba. It has also been recorded quite recently 

 by Dr. Vavra from another region of South America, viz., 

 from Chili. 



Distribution. — Besides from Australia and South 

 America, this form has been recorded by Prof. Birge from 



