Fresh-water Entomostraca of South America. 79 



41. Pleuroxus similis, Vavra, 



(PL XI, figs. 7, a— h). 



Pleuroxus similis, Vavra, Süsswasser-Cladoceren der Hamburger 

 Magalhaensische Sammelreise, p. 33. 



Specific Characters. — Female. Carapace, 

 seen laterally, oval triangular in form, height not equal to 

 the length, dorsal margin evenly arched, ventral angularly 

 curved in front of the middle, posterior extremity gradually 

 narrowed and truncated at the end. Head comparatively 

 small and procumbent, being, as in the other species, to a 

 certain extent mobile, rostral projection very long, acuminate, 

 and pointing obliquely behind. Surface of shell very faintly 

 reticulate, anterior part of valves, however, sculptured with 

 from 10 to 12 rather distinct curved transverse striæ, as in 

 P. aduncus Jurine, lower edges finely ciliated throughout, 

 infero-posteal corners each with 2 very small denticles. 

 Ocellus much smaller than the eye, and almost 3 times 

 nearer to it than to the tip of the rostrum. Antennulæ 

 comparatively short, scarcely reaching to the middle of the 

 rostrum. Lip-plate of moderate size, with the lower edge 

 evenly curved. Caudal part rather narrow, and conspicuously 

 tapering distaliy, supra-anal projection well marked and de- 

 fined below by a deep sinus, lower corner slightly produced 

 and narrowly rounded, marginal denticles rather strong, cau- 

 dal claws of moderate size, each with 2 denticles at the 

 base. Colour yellowish, changing to orange. Length of adult 

 female 0.48 mm. 



Remarks. — I think I am right in identifying this 

 from with the species recently recorded by Dr. Vävra Under 

 the above name. True, he does not mention the characteris- 

 tic striation of the anterior part of the valves, nor the deep 



