722 DR. A. GtXTHER Olf FISHES [JuTie 6, 



Nevertheless, having found that the extent of the dentition in the 

 species of this genus should be used as a taxonomic character 

 with great caution only, and all the more so the younger the speci- 

 mens are, I cannot make up my mind to employ a distinct name 

 for the Prah specimens, 



rig. 4. 



Chryskhthys biittiJcofcri (type). 



1 have before me one adult specimen 17 in. long, and four small 

 ones 5 or 6 in. long ; they were obtained at tlie same locality on 

 the Eiver Prah and at the same time, so that there cannot be any 

 doubt that all five belong to the same species. In appearance, and 

 especially in the form of the bead, the young differ so much from 

 the old that if they had been obtained at a more tlistant locality 

 it would have been impossible to recognize their specific afliinity. 



I therefore give here descriptive diagnoses of both adult and 

 young. 



Adult (PI. XLL). — The height of the body is contained 4^ times 

 in the total length (without caudal),the length of the head d\ ; caudal 

 peduncle two thirds as long as high. Head broader than high, its 

 greatest width being two tliirds of its length ; the greater portion 

 of its upper surface is covered with thin, soft skin, but the granu- 

 lated parts of the bones on the nape and crown of the head are 

 exposed or covered only with a thin film of skin ; occipital process 

 rather longer than the basal bone of the dorsal spine, both meeting 

 a little behind the nape. Snout rather long, narrowed towards the 

 end, depressed, its length being two fifths of that of the head; 

 upper jaw projecting beyond the lower ; mouth of moderate width, 

 as wide as the distance between the eyes. IS'asal barbels thin, 

 about as long as the eye ; maxillary barbels reaching beyond the 

 orbit, outer mandibulary barbels to the gill-opening ; mandibulary 

 barbels inserted in nearly the same straight line, the inner being 

 slightly anterior and less than a diameter of the eye distant from 

 each other. The teeth on the palate are confined to the vomer, 

 being placed in two ovate groups, which are less than half a dia- 

 meter of the eve distant from each other. The band of inter- 

 maxillary teeth tapers outward, each half being twice as broad as 

 long. The width of the bony interorbital space is more than that 

 of the orbit, which is two fifths of the length of the snout, and one 

 sixth of that of the head. Dorsal fin (mutilated) of moderate 

 heif^ht ; the length of its base is two fifths of its distance from the 

 adipose fin, and not quite twice as long as the base of the latter 



