300 siLUEnm 



2. HETEROBRANCHUS. 



Geoffroy, Descr. Egypte, Poiss. (1809), part. ; Giinther, Cat. Fishes, v. p. 21 (1864) ; 

 Boulenger, Poiss. Bass. Congo, p. 265 (1901). 



Distinguished from Clarias by the division of the dorsal fin into two parts, the 

 posterior adipose and supported by the prolongations of the neural spines. 



The accessory respiratory apparatus is the same as in Clarias, 



The vertebrae number 65 in a specimen of H. Mdorsalis, 61 in one of 11. longifilis 

 from the Nile, whilst Hyrtl * counted 57 in a specimen referred to Peters's H. laticeps, 

 which I regard as specifically identical with H. longifilis ; but it must be borne in 

 mind that Hyrtl reckoned the four anterior fused vertebrae as one. 



Three species from Africa, and one from the Malay Archipelago. 



1. HETEROBRANCHUS BIDORSALIS. 

 (Plate LIV. fig. 1.) 



L Geoffroy, Descr. Egypte, Poiss. p. 305, pi. xvi. figs. 2 & 5, and pi. xvii. figs. 8 & 9 (1827) ; 



Giinther, Petlierick's Trav. ii. p. 220 (1869). 

 Heterobranchus geoffroyi, Cuvier & Valenciennes, Hist. Poiss. xv. p. 392 (1844). 

 Heterohranchus senegalensis, Cuvier & Valenciennes, t. c. p. 397 ; Steindachner, Sitzb. Ak. Wien, 



lx. 1869, p. 980. 

 Heterobranchus intermedins, Giinther, Cat. Fish. v. p. 22 (1864), and 1. c. 



Depth of body six to nine times in the total length, length of head twice and 

 four-fifths to three and one-fourth times. Head very strongly depressed, once and 

 one-fourth to once and a half as long as broad, its upper surface coarsely granulate 

 in the adult ; occipital process pointed, sometimes very obtusely ; frontal fontanelle 

 knife-shaped, three to four times as long as broad, three to five times in the length 

 of the head ; occipital fontanelle small, in advance of the occipital process ; eye three 

 (young) to six and a half times in the length of the snout, six to ten and a half times in 

 the interorbital width ; width of mouth a little less than the interorbital width ; band 

 of prsemaxillary teeth about five times as long as broad ; vomerine teeth also villiform, 

 forming a crescentic band which is once and one-fourth to once and a half as broad as 

 the prsemaxillary band and may have a small central posterior process. Nasal barbel 

 two-thirds to once the length of the head; maxillary barbel four-fifths to once and 



* Denkschr. Ak. "Wien, xvi. 1859, p. 17. 



