100 CHARACINID.E. 



Depth of: body three and one-fourth to four and a half times in total 

 length, length of head three and a half to four and one-fourth times; 

 caudal peduncle once and one-third to once and two-thirds as long as 

 deep ; dorsal fin originating above or slightly in advance of ventral ; 



scales 44-48 4 2_ 5 1, 2 between lateral line and scaly process at base of 



ventral 2. H. lineatus, Blkr. 



Depth of body three and one-third to four and a half times in total length, 

 length of head three and one-third to four and one-fifth times ; caudal 

 peduncle once and two-fifths to once and two-thirds as long as deep ; 



gl_QA 



dorsal fin originating above first ray of ventral ; scales 47-54 \ L 2 , 



3 between lateral line and scaly process at base of ventral 3. H. hrevis, Gthr. 



1. HYDROCYON FORSKALII. 

 (Plate XVI. fig. 1 and Plate XVII. fig. 1.) 



Salmo dentex (non Hasselquist), Forskal, Descr. Anim. pp. xiii & 60 (1775). 



Characinus dentex, Greoffxoy, Descr. Egypte, Poiss. p. 49, pi. iv. fig. 1 (1809). 



Hydrocyon forslcalii, Cuvier, Mem. Mus. v. 1819, p. 354, pi. xxviii. fig. 1 ; Miiller & Troschel, Horse 



Ichthyol. i. p. 11, pi. iii. fig. 6 (1845) ; Giinther, Cat. Fish. v. p. 351 (1864), and Petherick's 



Trav. ii. p. 244 (1869) ; Steindachner, Sitzb. Ak. Wien ; lxi. i. 1870, p. 547 ; Vinciguerra, 



Ann. Mus. Genova, xxxvii. 1896, p. 29, and xxxix. 1898, p. 258. 

 Hydrocyon dentex, Riippell, Beschr. n. Fische Nil, p. 5 (1829). 

 Hydrocyon forskalii, part., Cuvier & Valenciennes, Hist. Poiss. xxii. p. 309 (1849) ; Peters, Reise 



Mossamb. iv. p. 69 (1868). 



Depth of body four to five and a half times in the total length, length of head 

 four to five times. Head twice to twice and a half as long as broad ; snout one-fourth 

 to one-third the length of the head; diameter of the eye four (youDg) to six and a 

 half times in the length of head, interorbital width three to four times; mouth 

 extending to below the nostrils, maxillary bone to below the anterior border or the 

 centre of the eye ; 5 or 6 large teeth in the upper jaw and 4 or 5 in the lower ; 

 suborbital and opercular bones smooth or feebly striated. Gill-rakers much shorter 

 than the gill-filaments, 8 to 10 on lower part of anterior arch. Dorsal fin with II 8 

 rays, equally distant from the end of the snout, the nostrils, or the eye, and from the 

 root of the caudal fin ; second simple ray longest, three-fourths to once and one-sixth the 

 length of the head. Adipose dorsal small, twice to twice and a half as dis + ant from the 

 rayed dorsal as from the caudal. Anal fin with III 11-13 rays, third simple ray 

 longest, one-half to three-fourths the length of the head. Pectoral fin about two- 

 thirds the length of head. Ventral fin as long as or shorter than the pectoral, below 

 middle of dorsal. Caudal fin deeply forked, with long, pointed lobes. Caudal 



