6 G. 0. Hårs. 



throughout. Colour, in the living state of the animal, 

 leathery brown, edges of carapace darker, eyes dark brown, 

 encircled by a broad, bright red margin, outer appendages 

 of the exposed legs beautiful coral-red. Length of fully 

 grown male (not including the caudal filaments) 30 mm.; 

 that of female about the same. 



Remarks. — The description given by Grube of his 

 Apus numidicus is certainly from a very young specimen of 

 only 18 mm. length, but I do not find anything in his 

 description and figure which could forbid an identification 

 of the South African form with that species. I am also 

 of opinion that the Apus dispar of Brauer 1 ) is the same 

 species; whereas the Apus sudanicus of the same author is 

 apparently distinct, being of less slender form, and having 

 a smaller number of caudal segments. From the Avell-known 

 European species Apus cancriformis the present species is 

 at once distinguished by the comparatively much smaller 

 size of the carapace, and the length and slenderness of the 

 exposed part of the body. In this respect it is much more 

 nearly related to the Australian species, Apus australiensis, 

 described by Messrs. Spencer and Hall 2 ), and in both these 

 species there is a much greater number of caudal (non- 

 pedigerous) segments present than in the European form, in 

 which only 7 such segments are found. 



General description of the male. 



The dimensions of the largest specimen examined are 

 as follows: ; 



*) Sitzungsberichte d. K. Akad. d. Wissensch. hi Wien, Vol. LXXV, 



Part 1, p. 589, PI. I. 

 2) Crustacea of the Horn Expedition, p. 231, PI. 20. figs. 1—3. 



