Fresh-water Entomostraca of South America. 71 



Biological Observations. — In some of my 

 aquaria this form developed very abundantly, and was ob- 

 served during 2 successive seasons. The specimens move in 

 the usual revolving manner, and were often seen attaching 

 themselves to the walls of the aquarium. Owing to the 

 greatly tumefied dorsal part of the carapace, it is rather 

 difficult to get an exact lateral view of the animal, as it 

 generally assumes a somewhat oblique position when brought 

 under the microscope in a small quantity of water, show- 

 ing more of the dorsal than of the ventral face. Male speci- 

 mens made their appearance at the close of the seasons, but 

 were not very numerous. 



Occurrence. — The aquaria in which this form 

 occurred, were all prepared with mud from the neighbour- 

 hood of Sâo Paulo. 



38. Cliydorus pubescens, n. sp. 



(PL XI, figs. 4, a— c). 

 Specific Characters. — Female: Carapace 

 of the usual subglobose shape, though distinctly truncated 

 behind, both the dorsal and ventral margins greatly bulging, 

 causing the height sometimes to be even greater than the 

 length. Head about as in the preceding species, though the 

 edges of the fornix appear more strongly curved, and the 

 rostral projection somewhat less produced. Surface of shell 

 distinctly reticulate in the lower part of the valves, dorsal 

 face thickly covered with short stiff hairs, forming, as it 

 were, a velvet-like coating of the shell; inner ciliated dupli- 

 catures of valves not far removed from the margin, hind 

 edges not double in contour. Ocellus smaller than the eye. 

 Lip-plate obtusely rounded at the tip. Caudal part of 



