Fresh- water Entomostraca of South America. 69 



The lip-plate is not, as indicated by Mr. Richard, quite 

 smooth, but in reality exhibits slight traces of the serrations 

 found in C. Barroisi (see fig. 2 b). 



Biological Observations. — This form de- 

 veloped rather abundantly in some of my aquaria, and was 

 observed during 2 successive seasons. In spite of the very 

 small size of the specimens, they could be easily distinguished 

 from C. Barroisi, even with the naked eye, by the different 

 manner in which they moved; for whereas in the latter the 

 movements are pronouncedly jerky, in the present species 

 they merely constitute a slow revolving leap through the 

 water, as in most other species of this genus. 



Occurrence. — The aquaria in which this form de- 

 veloped, were prepared with mud, partly from Itatiba, partly 

 from Sâo Paulo. 



Distribution. — As stated above, this form was 

 first described by Mr. Richard from Chili, and Mr. Vavra 

 has also recently recorded it from the southern part of Pata- 

 gonia, Tierra del Fuego, and the Falkland Islands; but this 

 form has not yet been noticed out of South America. 



(35. Chydorus spliæricus (Müller).) 



Remarks. — This form was found rather abundantly 

 in some of my aquaria; but as I am not quite sure, in 

 spite of the precautions taken, that it may not have been 

 accidentally transferred among the aquatic plants, I do not 

 insist on its claim to be considered as a member of the 

 Brazilian fauna. This species has, however, been recorded 

 from many places out of Europe, and also both from North 

 and South America, though in some cases a confusion with 

 nearly allied species may not be impossible. 



