354 SILUBID^E. 



straight or curved, feebly serrated behind, longitudinally striated and sharp-edged or 

 very finely granulate * in front, usually three-fourths to once the length of the head, 

 sometimes a little longer f , the soft terminal part usually produced into a short 

 filament. Adipose dorsal fin three to four and a half times as long as deep, twice and 

 one-third to four and a half times as long as its distance from the rayed dorsal. Anal 

 fin obtusely pointed in front, with 12 to 14 rays, 8 or 9 of which are branched. 

 Pectoral spine as long as or a little longer or a little shorter than that of the dorsal, 

 rarely reaching the root of the ventral fin, its outer border very finely, its inner border 

 strongly serrated (serrse 6 in the young to 32 in the adult). Ventral fin usually not 

 reaching the anal. Caudal fin deeply forked, the upper lobe longer than the lower, 

 sometimes prolonged into a filament. Caudal peduncle as long as deep or deeper 

 than long. 



Very young specimens, such as the one for which the name S. maculosus was 

 proposed by Ruppell, are handsomely marbled and spotted, wavy and oblique bands 

 of cream-colour or yellowish orange separating brown or greenish areas which bear 

 numerous round blackish-brown spots ; two or three more or less regular yellowish 

 streaks along the snout; fins with dark brown spots; a more or less regular dark 

 brown band on each lobe of the caudal fin ; barbels white or pinkish. These markings 

 gradually disappear with age, and are usually replaced, in specimens of 100 to 200 

 millim., by very numerous minute dark dots on the upper parts and on the adipose 

 dorsal fin. Adults are uniform grey, bluish, brown, or olive above and white beneath, 

 the paired fins and the anal sometimes blackish. Some half-grown specimens are of a 

 dull uniform yellowish-orange colour. 



Albinism, partial or complete, appears to be comparatively frequent in this species. 

 Colourless, flesh-coloured specimens were found at Cairo and at Wady Haifa by 

 Mr. Loat, but the albinism did not affect the eye, the pupil of which was black. 

 Albinos, of different degrees, were observed by Capt. Flower at Giza. Some, after 

 having been kept in an aquarium, have gradually turned dark, or have become piebald, 

 some being pinky white on the body, with the head and the fins of a rich black, while 

 others have become dark all over. A piebald specimen, it must be observed, was at 

 first a perfect albino, with pink pupil (a rare occurrence in fishes), but the eyes in the 

 course of time have turned from pink to black J. 



A piebald specimen of large size, from the Baro River, is in Mr. Zaphiro's collection. 



The Schall is not known to exceed a length of 410 millimetres. 



Syi2odontis schall has a wide distribution, being know^n from the whole Nile, Lakes 

 Abaia, Stephanie, and Rudolf, Lake Chad, and the Senegal. The Senegalese specimens 



* This granulation sometimes approaching to a serration. 



t See ]S"os. 8 and 10 of table of measurements. 



J Cf. S. Flower, 7th Ann. Eep. Zool. Gard. Giza (Cairo, 1906), p. 31. 



