Fresh-water Entomostraca of South America. 57 



preceding species, though the rostral projection appears some- 

 what more produced. Surface of shell without any striæ, but 

 with scattered, rather prominent, rounded tubercles arranged 

 in a concentric manner. Ocellus smaller than the eye, and 

 placed much nearer to it than to the tip of the rostrum. 

 Lip-plate with a very conspicuous angular projection in front 

 of the middle. Caudal part unusually short and robust in 

 form, not widening distally, dorsal edge below the anal ori- 

 fice slightly curved, supra-anal projection well marked, and 

 occurring near the middle, lower corner not produced, but 

 broadly rounded, margiual denticles extremely small, lateral 

 ones considerably larger, numbering about 10 on each side, 

 caudal claws with a very small denticle at the base. Body 

 pellucid, with a faint yellowish tinge. Length of adult female 

 0,36 mm. 



Remarks. — In its external appearance this form 

 somewhat recalls A. intermedia (see fig. 4), the carapace be- 

 ing of a similar short and broad form. The sculpture of 

 the shell, however, is very different, and also the shape of 

 the caudal part is rather dissimilar. Moreover, the angular 

 projection of the lip-plate distinguishes this form from all 

 the other known species. 1 have found the peculiar tuber- 

 culated sculpture of the shell, which has given rise to the 

 specific name here proposed, to be constant in all the speci- 

 mens examined; and this is especially apparent, when one 

 of the valves is out of the water. It somewhat resembles 

 that found in A. guttata; but the tubercles in the present 

 species are much coarser and less crowded together. 



Occurrence. — This form was not unfrequently 

 taken up in the dipping-tube from some of my aquaria pre- 

 pared with mud from the neighbourhood of Sâo Paulo. 



