BRANCHIURA FROM LAKE TANGANYIKA. 277 



Remarks. — This species, which in some features comes near to 

 the preceding one, may be readily distinguished from it by the 

 rounded nature of the abdominal lobes. The reddish coloration, 

 which is strilcing in the larger specimens, is less evident or almost 

 entirely absent in smaller ones. All the mn.le specimens in the 

 collection, which are rather small, show little colour, except, of 

 course, the characteristic blotching of the testes. It will be 

 noticed that this form has only been obtained from the Siluroid 

 Chrysichthys hrachynema, which is itself an endemic species. 



Occurrence.— Wolivo, 24/10/04. From roof of mouth of fair- 

 sized Chrysichthys hrachynema. One female. 



Kibwesi, 19/12/04. From head, mouth, and gill-bars of several 

 large Chrysichthys hrachynema. Thi'ee males and nine females, 

 associated with specimens of A. striatus. 



Mrumbi, 27/12/04. From inside mouth and outside body of 

 large Chrysichthys hrachynema. One male and one female 

 specimen. 



Argulus africanus Tliiele. 



Argulus africanus Thiele, Zool. Anz. vol. xxiii. 1901, p. 47. 



Argulus africarms Wilson, Proc. U.S. Nat. Mus. vol. xxv. 190.3, 

 p. 727. 



Argulus africanvjS Thiele, Mitt. Zool. Mus. Berlin, Bd. 2, 

 Heft 4, 1904, p. 37. 



A preliminary description of this form was given by Thiele in 

 1901, and was followed by a more complete account with figui'es 

 in 1904. It is the only species of the genus Argulus which had 

 been previously obtained from the continent of Africa, and it 

 still remains the only species known outside the confines of Lake 

 Tanganyika. Tliiele speaks of it as a form widely distributed in 

 eastern Africa, and it is now possible to add other localities to 

 those hitherto known. 



As I have examined more than 60 specimens from different 

 pai-ts of Africa, perhaps I may add a few remarks in modification 

 of Thiele's detailed description. Between the average male and 

 female specimens there is by no mea.ns so clear a contrast as he 

 indicates in the relative proportions of the carapace (cephalo- 

 thorax). It is a fact, as I have determined by actual measui^e- 

 ments, that the carapace of a large female is broader in proportion, 

 and so less closely resembles the male condition, but except 

 in extreme cases of large females contrasted with small males, 

 there is but little difference in this respect between the two 

 sexes. 



Again, the carapace lobes in the female are stated to cover the 

 whole of the swimming-legs, leaving but the tips of the last two 

 pairs visible from above. This may, perhaps, be the condition 

 of things in an individual gTea,tly distended with eggs, but is 

 neither normal nor typical. In the great majority of the 

 females in this collection, the tips of all four pairs of swimming- 

 legs project from beneath the carapace, and in a few cases the 



