HTDEOCYON. 



99 



bone followed by 1 to 3 small ones ; each side of the lower jaw bears 3 to 5 large teeth 

 and 1 or 2 small ones; the replacement-teeth, fully developed but lying flat in a 

 sort of socket, form a complete series behind the functional one. 



The vertebra?, in H. forskalii, vary from 49 to 52,-32 to 34 praecaudals and 17 or 

 18 caudals ; I find 31 of the former and 18 of the latter in a specimen of 

 H. brevis. 



The air-bladder is large and its posterior chamber about three times as long as the 

 anterior; it does not extend into the caudal region ; the pneumatic duct opens on the 



Fig. 16. 



Hydrocyon forskalii : upper view of skull of half-grown specimen and inner view of lower jaw of adult. 



left side. As in other strictly carnivorous forms, the digestive tract is shorter than 

 the fish ; the pyloric appendages are large and numerous, the posterior forming a fringe 

 to the intestine for about one-sixth of its length. 



Large, ferocious, carnivorous fishes inhabiting the rivers and lakes of Africa, from 

 the Nile and Senegal to the Congo and the Limpopo, and represented by five very 

 closely-allied species, three of which occur in the Nile, whilst the two others, H. cjoliath, 

 Blgr., and H. vittiger, Blgr., are only known from the Congo. 



Synopsis of the Species. 



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

 four to five times ; caudal peduncle once and two-thirds to twice as 

 long as deep; dorsal fin originating in advance of ventral; scales 



7-4-8 x 

 48-54 |rqj|, 2 between lateral line and scaly process at base of 



ventral 1. H. forskalii, Cuv. 



02 



