72 



SILURIDiE. 



having the upper side of the head covered with thin skin only, so 

 that portions of the bone are nearly naked and granulated ; its eye 

 is considerably larger, the diameter being more than one- fifth of the 

 orbit. The first dorsal ray and the upper caudal lobe are prolonged 

 into filaments. 

 Upper Nile. 



a. Adult. Nile. Presented by Dr. Ruppell. 



b-f. Adult and half-grown. Chartoum. From Consul Petherick's 



Collection. 

 y. Adult : skeleton. Chartoum. From Consul Petherick's Collection. 



The largest of our examples is 7 inches long, without caudal ; its 

 head is 24 lines, and its eye 6 lines long ; so that a comparison with 

 the measurements given of 0. auratus will show that the latter spe- 

 cies has an absolutely snialler eye. 



Although both species are so similar that Dr. Ruppell appears to 

 have considered them identical, yet they would enter two different 

 genera of Dr. v. Bleeker's system. 



3. Chrysichthys maurus. 

 Bagrus maurus, Cuv. Sf Val. xiv. p. 431. 



D. 1/6. A. 10-11. 



The head is entirely covered with soft skin. The height of the 

 body is nearly one-sixth of the total length (with the caudal), the 

 length of the head one-fifth. The teeth on the palate are in two 

 short, nearly transverse lines. Dorsal spine as high as the body 

 and half as high as the soft rays ; pectoral spine strongly serrated. 

 Adipose fin half as long as the anal. Dark- coloured. (Veil.) 



Senegal. 



4. Chrysichthys cranchii. 



Pimelodus cranchii, Leach, in Tucket/, Narrat. Exped. Zaire, p. 409 ; 



Griff. An. Kingd. Fish. Suppl. pi. 40. 

 Bagrus nigrita, Cuv. 8/ Val. xiv. p. 426. pi. 416. 



D. 1/6. A. 13. P. 1/9. V. 6. 



The height of the body is one-fifth of the total length (without 

 caudal), the length- of the head one-third ; head much -broader than 

 high, its greatest width being three-quarters of its length. Crown 

 of the head striated ; occipital process nearly as long as the basal bone 

 of the dorsal spine, both meeting in the, middle of the neck. Snout 

 broad, depressed, spatulate, its length being one-third of that of the 

 head ; jaws nearly equal in length. Vomerine teeth in two separate 

 broad patches, each patch being confluent with the band of palatine 

 teeth of its side. Nasal barbels very short and thin, maxillary barbels 

 as long as the head ; mandibulary barbels rather short, the outer twice 

 the length of the inner. Dorsal fin as high as the body ; its spine is 

 of moderate strength, not 'serrated, and not quite half as long as the 

 head. Adipose fin considerably shorter than the dorsal ; its distance 

 from the dorsal equals twice the length of the base of the latter. 



