HTPEKOPISTJS. 71 



scaly on at least two-thirds of its extent, with obtusely pointed lobes. Caudal 

 peduncle twice to twice and two-thirds as long as deep, nearly one-half to two-thirds 



17-94 



the length of the head. 93 to 120 scales in the lateral line, ^io in a transverse series 

 on the body, j^ 2 between dorsal and anal fins, 20 (rarely 18 or 22) round the 

 caudal peduncle. 



The upper parts are greyish olive or purplish or greenish brown, with strongly 

 iridescent sheen, the lower parts white; the thin skin which covers the scaly 

 integument, and which becomes readily detached in spirit-specimens, is often spotted 

 with black. The fins are greyish white, according to a coloured sketch made by 

 Mr. Loat, whilst in specimens from the Senegal, sketched by the late P. Delhez, they 

 are yellowish with the pectoral and caudal tinged with bright red at the base. Iris 

 silvery. 



The largest specimen examined by me measures 460 millimetres. One observed, 

 but not preserved, by Mr. Loat at Wad Medine, Blue Nile, measured 520 millim. 



West- African specimens have been separated under the name of II. occidentalism 

 Gthr., on characters which, as pointed out by Steindachner, are not sufficiently 

 constant to justify such a course. But it must be admitted that specimens with as 

 few as 12 dorsal rays and as many as 65 anal rays, as in the type of II occidentalism 

 from the Niger, have not been found in the Nile. I have counted the rays in fifty 

 specimens from the Nile, and found 13 dorsal rays three times, 14 twenty-eight times, 

 15 seventeen times, and 16 twice; 58 anal rays four times, 59 eight times, 60 twenty-one 

 times, 61 nine times, 62 six times, and 63 and 64 once. Whilst on fifteen specimens 

 from West Africa (Senegal, Gambia, Niger), 12 dorsal rays occur once, 13 six times, 

 14 and 15 four times ; 59, 60, 62, and 63 anal rays once, 64 six times, and 65 and 67 

 twice. The range of variation in Nile specimens is therefore D. 13-16, A. 58-64, and 

 in West-African specimens I). 12-15, A. 59-67. The specimen from the Chad Basin 

 has 13. 15, A. 60. I cannot endorse Steindachner's statement that young examples 

 have, as a rule, one or two ravs less than the adult in both dorsal and anal fins. 



The habitat of this species is known to extend over nearly the entire Nile system, 

 from the Delta to Wadelai and Wad Medine, the Chad Basin, the Senegal, the Gambia, 

 and the Niger. 



List of specimens examined : — 



4 Lower Nile.— S. S. Allen, 1861. 



2 Barrage N. of Cairo.— Loat, 16.10.99. 



3 Beni Souef.— Loat, 28.8.99-1-9.9.99. 



2 Between Beni Souef and Biba.— Loat, 7.9.99. 



18 At regulators near Luxor.— Loat, 20.10.00-10.11.00. 



3 Khartum.— Petherick, 1862. 



1 Wad Medine, Blue Nile.— Loat, 10.10.01. 



