Fresh-water Entomostraca of South America. 77 



lower corner obsolete, marginal denticles rather small and 

 hair-like, and accompanied by several transverse rows of still 

 smaller lateral denticles, caudal claws comparatively short 

 and much curved, with a well-marked denticle at the base, 

 distal part smooth. Colour light yellowish white. Length 

 of adult female 0.46 mm. 



Remarks. — This form very closely resembles D. 

 crassa, King, described by the present author from Austra- 

 lia. It is, however, at once distinguished by the peculiar 

 dentiform projection of the lip-plate, a character which has 

 given rise to the specific name here proposed. Moreover, 

 the colour is much paler, and the surface of the shell, which 

 in the Australian species is perfectly smooth, exhibits a dis- 

 tinct, though not very sharply marked reticulation. The 

 form recently recorded by Mr. Vavra from Chili as D. seti- 

 gera Birge, is unquestionably the same species, as shown 

 by the figure of the lip-plate given; and this is certainly 

 also the case with the South American form recorded by 

 Mr. Richard, and likewise identified with the North Ameri- 

 can species. As, however, neither Prof. Birge nor Herrick 

 mention any dentiform projection on the lip, and the figures 

 given do not exhibit any trace of such a projection, I find 

 that an identification of the two forms with one another is 

 inadmissible. On the other hand, it is not improbable that 

 the European form recorded by Mr. Daday and Stingelin is 

 in reality identical with Birge's species. I have myself had 

 an opportunity of examining a species from Algiers, different 

 from both the Australian and the South American form, but 

 in all probability the same as that occurring in Europe and 

 North America, and have convinced myself, that it alto- 

 gether lacks the dentiform projection of the lip-plate, so 

 characteristic of the species in question. 



