GYMNARCniD.E. 225 



Fam. 11. GYMNARCHID^. 



Body and tail scaly, head scaleless; barbels none.' 

 The margin of the upper jaw is formed in the middle 

 by the intermaxillaries, which, in mature individuals, 

 coalesce into a single bone, and laterally by the max- 

 illaries. Sub- and interoperculum present, small ; 

 on each side of the parietal bone a cavity leading into 

 the interior of the skull, and covered with a thin bony 

 lamella. Dorsal fin extending nearly over the entire 

 length of the back ; tail tapering, without fin ; anal 

 and ventral fins absent. Vent nearly in the middle 

 of the length of the fish. A series of pores along the 

 base of the dorsal fin. Pseudobranchise none; gill- 

 opening reduced to a slit on each side. Two cseca 

 pylorica behind the stomach. 



Rivers of Tropical Africa. 

 One genus only. 



1. GYMNARCHUS. 

 Gymnarclms, C'uv. R^(/)ie Anim. 

 Each jaw with a single series of incisors ; no teeth on the palate. 

 Air-bladder cellular, very extensible, perhaps with the functions of 

 a lung. 



1. Gymnarchus niloticus. 



.leifar, Rifaud, Voy. Ef/ypte, pi. 1.'38b. fig. 1 (bad). 



G}aiinarclius niloticus, Cuv. Ee(/ne Anim. ; Erdl, Ahliandl. Bcn/r. Akad. 

 Wiss. 1847, p. 209 (osteol.)'; TIeckel, Denkschr. Akad. Wiss. Wien, 

 1854, vi. p. 11, taf. 1-2; Hyrtl, Denkschr. Akad. Wiss. Wien, 1850, 

 xii. p. 1, 0. lab. (anat. and osteol.). 



D. 203-208. 



The length of the head is contained four times and one-third in 

 that of the dorsal fin, and once and two-thii-ds in its distance from 

 the vent. Seven teeth on each side of the intermaxillary. Pectoral 

 fin rather shorter than the snout. 



Nile ; rivers of West Africa. 

 a. Adult. Upper Nile. From Mr. J. Pethcrick's Collection. 

 h-c. From four to five feet long : stuffed. West Africa. Purchased 



of Mr. Dalton. 

 d. Fine half-grown specimen. West Africa. Purchased of Mr. Dalton. 

 e,f. Young, 11 inches long. West Africa. 

 (j. Adult. Purchased of Mr. Frank. 

 h. Adult : stuffed. Purchased of M. Parzudaki. 

 i. Skiill of specimen h. 



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