Fresh-water Entomostraca of South America. \± 



slightly ascending; inner duplicatures of valves very fully 

 developed, and easily observable both in the lateral and 

 ventral aspects of the animal. Head well defined from the 

 carapace, and, seen laterally, rather narrow, very slightly 

 tapered distally, and obliquely truncated at the end, frontal 

 part scarcely protuberant at all. Eye exceedingly large. 

 Antennæ rather powerful, though, when reflexed, not reaching 

 to the hind edge of the carapace, terminal joint of upper 

 ramus with 8 natatory setæ. Tail of the usual structure, 

 caudal claws finely denticulate in their distal part, basal spines 

 rather small and rapidly diminishing in size proximally. 

 Resting ova very dark, globose, and clothed all over with 

 small spiniform processes. Male much smaller than female, 

 dorsal margin of carapace straight, cardial region gibbously 

 convex, head more bluntly rounded at the end. Antennulæ 

 transformed in the usual manner, but considerably shorter 

 than in the European species, not nearly attaining half the 

 length of the body. First pair of legs terminating in a 

 rather small, and only very slightly curved hook. Sexual 

 appendages extending slightly beyond the base of the caudal 

 claws, and simply truncate at the tip. Body in both sexes 

 highly pellucid and almost colourless. Length of adult 

 female 0.80 mm., of male 0.66 mm. 



Remarks. — I can see no difference between the above- 

 characterised Brazilian form, and that described by Mr. 

 Richard from Sumatra, and I am therefore induced to believe 

 that the two are in reality identical, in spite of the great 

 distance between their finding-places. Similar proofs of an 

 extraordinary geographical distribution will also be stated 

 below in the case of other Brazilian Cladocera. The present 

 species is nearly allied to the Australian form, D. excisum 

 G. O. Sars, but differs in the somewhat deviating form of 



