322 



SILUEID.E. 



about one-third the length of the head, narrowly separated from the caudal fin, which 

 is deeply forked, with pointed lobes. 



Fig. 27. 



Physailia pellucid a. Natural size. 



Colourless, translucent in life, the air-bladder showing through the thin skin ; minute 

 black dots may be present on the vertebral line and near the anal fin. 



104 specimens, varying in length between 67 and 93 millimetres, were obtained on 

 May 29th, 1901, by Mr. Loat at Omdurman, at the junction of the Blue and White 

 Niles, in fairly deep water, 10 to 15 yards from the bank. 



Measurements (in millimetres). 



Total length 93 



„ „ (without caudal) S6 



Greatest depth 20 



Length of head 13 



Width of head 8 



Length of snout 3| 



Diameter of eye 4 



Interocular width 5 



Width of mouth 4 



Nasal barbel 26 



Maxillary barbel 27 



Mandibular barbel 29 



Length of pectoral fin 13 



P. occidentalism Pellegrin, is, as pointed out by its describer, very similar to the Nile 

 species ; the only difference revealed by the description resides in the smaller number 

 of anal rays, viz. 61. P. somalensis, Vinciguerra, is described as having the pectoral 

 spine non-serrated and the barbels about half as long as the head and body. 



