ALESTES. 115 



to 51 (usually 45 to 50) Sg^, 2 or 2J between the lateral line and the root of the 

 ventral fin. 



Apart from the shape of the mouth and the dentition, this fish bears a considerable 

 general resemblance to Hydrocyon forskalii, and it likewise usually has the lower lobe 

 of the caudal fin of a bright red. The body is silvery, the back dark grey or dark 

 sage-green ; a more or less distinct darker band may be present along each side of the 

 back. In some specimens, Mr. Loat observes, the red on the ventral fins is very faint, 

 and there is only a little on the anal ; the young have red on the caudal fin only ; the 

 latter fin is often edged with blackish; the iris is silvery or golden, the amount of 

 yellow varying a good deal according to individuals. 



The largest specimen measures 400 millimetres. 



Having counted the branched rays in the anal fin and the scales in the lateral 

 line in fifty specimens, I find one with 19 rays, seventeen with 20, seventeen 

 with 21, twelve with 22, and three with 23; two with 44 scales, eight with 45, 

 six with 46, six with 47, seven with 48, eight with 49, twelve with 50, and one 

 with 51. 



The above description is taken from Nile specimens. The specimens from West 

 Africa (Senegal, Gambia, Niger) often have a shorter body and have been distinguished 

 as a separate species under the name of A. sethente, C. & V. But this character 

 is by no means constant, and, as may be seen from the above table of measurements, 

 some of these western specimens cannot be distinguished from the typical A. dentex, 

 so far as the proportions are concerned, whilst specimens occur at Omdurman which 

 would fall under the definition of A. sethente ; having failed to discover any other 

 points by which they could be separated, I must regard A. sethente as a mere form of 

 A. dentex. The depth of the body is contained three and one-fourth to four and one- 

 fifth times in the total length, the length of the head four and one-eighth to five and 

 one-third times. Anal HI 17-21. Scales 45-49 ^. For measurements, &c, see p. 116. 



Alestes dentex inhabits the whole Nile, from its mouth to the Lake Albert. It is 

 also on record from Lake Rudolf *. Mr. Loat found it common in the Fish Bazars at 

 Cairo, and also states that it is " Fairly numerous in Lakes Menzaleh and Borollos 

 during the high Nile, in Lake Edkou during the high Nile only, and then only a few. 

 At Rosetta most are taken about Christmas-time, when the Nile is going down. It is 

 fairly numerous in the Birket Karun, in the Fayum. In trenches and pools it is often 

 very plentiful, but of a small size. Plentiful in the Bahr Yusuf, in the Fayum, when 

 the Nile is going down." It has not been recorded from the Blue Nile. It is common 

 in the Senegal and the Gambia, and occurs also in the Niger and in the Lake Chad 

 Basin. 



* PellegriD, Bull. Mus. Paris, 1905, p. 291. 



