TILAPIA. 525 



to once and one-third the length of the head, extending as far as the origin of the 

 anal, or beyond. Ventral fin reaching the vent or the anal. Caudal fin truncate in 

 the young, rounded in the adult. Caudal peduncle a little deeper than long. Scales 

 not denticulate, 31-35 jgg ; lateral lines y^Ys *• 



Specimens in spirit are yellowish or brownish, some or most of the scales often 

 darker at the base, or lighter in the centre, young specimens with eight or nine more 

 or less distinct dark bars on the body and a dark spot just below the upper border of 

 the caudal peduncle ; a blackish opercular spot ; dorsal and anal fins with blackish 

 and whitish spots forming oblique series, or with oblique dark streaks ; caudal fin with 

 more or less distinct dark bars, variable in number. In life the coloration varies from 

 whitish or pale silvery grey to dark olive, the belly being usually white ; a dull purplish- 

 red colour may extend over the head and on the lower parts of the body ; the dorsal, 

 anal, and caudal fins may be edged with bright reel. Some adult specimens, from Lake 

 Suksuki, are much spotted with black, and one young, 75 millim. long, from Lake 

 Menzaleh, described by Mr. Loat in his notes as a u black variety," is of a very dark 

 brown, just showing the usual darker markings. 



A coloured sketch of an adult specimen made by Mr. Degen on Lake Tsana 

 represents the fish as of a pale grey, with small olive-brown and blue spots, the 

 praeoperculum and the gill-cover with a dull red border, the bases of the dorsal 

 spines bright yellow, the iris grey, with a bright yellow circle round the pupil. Very 

 young specimens have a round black spot on the anterior part of the soft division of 

 the dorsal fin, as in T. zillii, variabilis, and galilcea. 



Our largest specimen measures 460 millimetres. Dr. J. C. Mitchell records a 

 specimen from the Fayum measuring 530 millimetres. 



The distribution of this species is a very extensive one, ranging from Lake Galilee 

 and the Jordan southwards to the Great Lakes and East Africa, westwards through 

 the Chad Basin to the Senegal and Niger. I have before me the following series of 

 specimens : — 



2 Lake Galilee. — Canon Tristram, 1864. 



15 Lake Mareotis.— Loat, 12.11.99. 



20 Lake Edkou.— Loat, 29.10.99. 



6 Lake Borollos, in freshwater canal. — Loat, 7.11.99. 



2 Lake Menzaleh.— Dr. J. 0. Mitchell, 1895. 



15 Lake Menzaleh.— Loat, 25.4-18.6.99. 



8 Ghet-el-Nassara, near L. Menzaleh.— Loat, 29.4-11.6.99. 



8 Bahr-el-Tawilah, near L. Menzaleh.— Loaf, 26-29.6.99. 



1 Nile.— Euppell, 1833. 



6 Lower Nile.— Petherick, 1861. 



* The lower lateral line is entirely absent in a specimen from the mouth of Lake No. 



