HETEROBRANCIItrS. 



273 



1. HETEROBRANOHUS BIDORSALIS. 



I. Geoffr. Descr. Egypte, Poiss. p. 305, pi. xvi. figs. 2 & 5, & pi. xvii. figs. 8 & 9 

 (1827) ; Giinth. Petherick's Trav. ii. p. 220 (1869) ; Bouleng. Fish. Nile, 

 p. 300, pi. liv. fig. 1 (1907), and Proc. Zool. Soc. 1907, p. 1095. 



Heterobranclms geoffroyi, (luv. & Val. Hist. Poiss. xv. p. 392 (1840). 



Heterobranclms senegalensis, Guv. & Val. t. c. p. 397 ; Steind. Sitzb. Ak. Wien, lx. 

 1869, p. 980. 



Heterobranclms intermedins, Giinth. Cat. Fish. v. p. 22 (1864), and 1. c. 



Depth of body 6 to 9 times in total length, length of head 2-f to 3j 

 times. Head very strongly depressed, 1^ to 1^ times as long as broad, 

 its upper surface coarsely granulate in the adult; occipital process 

 pointed, sometimes very obtusely; frontal fontanelle knife-shaped, 3 to 

 4 times as long as broad, 3 to 5 times in length of head ; occipital 

 fontanelle small, in advance of occipital process ; eye 3 (young) to 6^ 

 times in length of snout, 6 to 10^ times in interorbital width ; width of 

 mouth a little less than interorbital width ; band of prsemaxillary teeth 

 about 5 times as long as broad; vomerine teeth also villiform, forming a 



Fig. 226. 



HeterobrancJius bidorsalis. 

 "White Nile (F. N.). J-. 



crescentic band which is 1^ to 1J times as broad as the prsemaxillary 

 band and may have a small central posterior process ; nasal barbel f to 

 once length of head ; maxillary barbel f to If times length of head, 

 extending to extremity of pectoral or between this point and root of 

 ventral ; outer mandibular barbel 1-^- to 1J times as long as inner, 

 which measures 1 to li times length of head. Gill-rakers rather 

 short, 20 to 30 on anterior arch. Dorsal 38-45, its distance from 

 occipital process ^s to ^ length of head ; adipose dorsal f to f as long 

 as, as deep as or lower than, and commencing immediately behind, 

 rayed dorsal, extending to base of caudal. Anal 50-57, extending to 

 base of caudal. Pectoral f to § length of head, the spine smooth 

 VOL. II. T 



