BABILIUS. 261 



5. BARILIUS. 



Barilius, part., Hamilton Buchanan, Fishes Ganges, p. 384 (1822). 

 Opsaridium, Peters, Mon. Berl. Ac. 1853, p. 783, and Reise Mossamb. iv. p. 58 (1868). 

 Pelotrophus, Gunther, Proc. Zool. Soc. 1864, p. 314, and Cat. Fishes, vii. p. 320 (1868). 

 Barilius, Gunther, Cat. Fish. t. c. p. 286 ; Boulenger, Poiss. Bass. Congo, p. 231 (1901). 

 Engraulicypris, Gunther, Proc. Zool. Soc. 1893, p. 626. 



Body more or less compressed, with rounded belly, covered with small or moderately 

 large scales. Lateral line low down, following the ventral outline of the body and 

 running along the lower part of the caudal peduncle. Mouth large, oblique, without 

 lips, with or without barbels *. Suborbitals large, covering the whole or the greater 

 part of the cheek. Gill-membranes narrowly united to the isthmus. Dorsal fin 

 without ossified ray, with 9 to 13 rays, 7 to 10 of which are branched, originating 

 behind the vertical of the ventrals and before that of the anal. Anal fin with 12 to 22 

 rays. A scaly process at the base of the ventrals. Pharyngeal teeth conical, hooked, 

 in two or three series. 



The bones of the skull are rather thin ; a large supraorbital bone is present and 

 articulates with the postorbitals ; the prsemaxillary and the maxillary are much 

 elongate, the latter extending to or a little beyond the extremity of the former; the 

 occipital crest is very low and short. The vertebrae number 36 to 48. The following 

 are the numbers in the two Nile species : — 



B.niloticus 19 + 17 = 36 



B.loati 22 + 22 = 44 



The air-bladder of B. niloticus is peculiar in its second division being narrow and 

 tube-like, a condition very similar to that observed by Mr. Rowntree in Nannocharax ^ . 

 The digestive canal is short. In a specimen measuring 60 millim., without the caudal 

 fin, and the body-cavity 28, the anterior chamber of the air-bladder measures 6 in 

 length and 5 in diameter, the posterior 7 in length and 1 in diameter, the digestive 

 canal 50. In B. loati the posterior chamber of the air-bladder is not so much 

 reduced, but is comparatively small for a Cyprinid; although rather broad in front 

 it tapers to a narrow tube behind, and its whole length is only a little greater than 

 that of the anterior chamber. 



In both the Nile species there are 15 or 16 rays in the pectoral fin and 10 

 (8 branched) in the ventral. 



The genus Barilhis is represented by about twenty species in South-eastern Asia and 



* Barbels are absent in all the African species, 

 t Tr. Linn. Soc. (2) Zool. ix. 19U3, p. 60. 



