LATES. 453 



occiput with large scales ; prseopercular border forming nearly a right angle, finely 

 serrated on its vertical limb, with three or four strong spines on its lower limb, and 

 with one or two still stronger spines at its angle ; a single opercular spine ; clavicle 

 with some strong denticulations above the base of the pectoral fin. Gill-rakers rather 

 long, 15 to 17 (including knob-like rudiments) on lower part of anterior arch. Dorsal 

 fin with 7 or 8 spines in the first division and 1 or 2 spines and 10 to 14 soft rays 

 (usually 11 or 12 in specimens from the Nile) in the second* ; spines strong, first and 

 second short, third very strong, longest one-third (adult) to two-thirds (young) the 

 length of the head, usually as long as or longer than the longest soft rays. Anal fin 

 with 3 spines and 8 or 9 (rarely 7) soft rays ; spines short, third longest. Pectoral fin 

 nearly one-half to three-fifths the length of the head. Caudal fin rounded. All the 

 soft rays of the vertical fins more or less densely scaled, at least at the base. Caudal 

 peduncle as long as deep or a little longer than deep. Scales rugose with small 

 denticles on the posterior part of the exposed surface, 60 to 80 in the lateral line, 



8-12 . 



12=24 in a transverse series. 



Uniform brown or olive above in the adult, silvery beneath, sometimes tinged with 

 yellow, young usually (occasionally up to a length of 250 millimetres) marbled 

 with brown, sometimes uniform ; very young specimens (under 70 millimetres) with 

 more or less irregular dark brown cross-bands, the first of which extends on the 

 deepest part of the dorsal fin ; fins whitish, dark at the base in the young. Mr. Loat's 

 sketch of one of these young, 70 millimetres long, is pale lilac above, the marblings 

 and bars black; iris greyish. 



Specimens from the Congo have the scales rather larger, therefore less numerous 

 (60-70 ^2^) than those from the Nile (65-80 jt^), and the soft dorsal rays number 

 12 to 14. I have counted the fin-rays in fifty specimens from the Nile and find the 

 dorsal formula to be once VII, I 13, twice VII, 1 11, three times VIII, I 12, ten times 

 VII, II 11, sixteen times VII, I 12, and eighteen times VIII, 111; anal soft rays 

 twice 7, ten times 9, and thirty-eight times 8. 



According to Dr. Steindachner, this fish reaches a length of 1 m. 80 in the Senegal, and 

 Mr. Loat mentions having seen one of the same size from the Sobat. Mr. J. J. Lister 

 has submitted to me a photograph of a specimen from the Birket-Karun, Fayum, 

 measuring 1 m. 27, and a skeleton from the same lake presented to the British Museum 

 by Dr. John Anderson (figured PL LXXXV. d) measures 1 m. 40, the weight of such 

 a fish being 140 lbs. 



Lates niloticus has a wide distribution, being found throughout the Nile from its 

 mouths to Lake Albert, where it was first observed by Sir Samuel Baker f (but 



* The two divisions being connected at the base it is often somewhat arbitrary to decide whether one 

 of the intermediate spines belongs to the first or to the second, 

 t The Albert N'yanza, ii. p . I3i } fig. (1866). 



