SILTTBIDjE. 189 



posterior provided with a valve. A single row of compressed teeth, 

 which are subtruncated or almost tricuspid in the jaws ; palate 

 edentulous. Dorsal fin with one spine and seven rays, inserted 

 nearer the snout than the ventrals are ; adipose fin short ; anal of 

 moderate length and not continuous with the caudal, which latter 

 is forked. Ventral with six rays. Air-bladder not enclosed in 

 bone. An axillary pore. 



Geographical Distribution. Andamans to the Malay Archipelago. 



202. (1.) Ketengns typus. (Pig. 68.) 



Ketengus typus, Sleeker, Atl. Ich. ii, p. 44, t. 82, fig. 1 ; Day, Fish. 

 India, p. 468, pi. cviii, fig. 2 (see synon.). 



B. v. ^D. 1/7 | 0. P. 1/7-8. V. 6. " A. 19-20 (5-6/14). C. 15. 



Length of head 4|, of caudal fin 5|, height of body 5| in the total 

 length. Eyes diameter 5| in the length of head, 1| diameters 

 from end of snout, and 2| apart. The greatest width of the head 

 equals its length excluding the snout. Upper surface of the head, 

 occipital process, and basal bone of the dorsal fin densely granulated. 



Fig. &. Ketengus typus. 



The width of the gape of the mouth equals the length of the head 

 excluding the snout. Longitudinal groove along the upper surface 

 of the head deep but narrow, commencing on the snout it is not 

 continued so far as to the base of the occipital process which is as 

 long as wide at its base. Teeth as defined in the genus. Fins 

 dorsal spine as long as the head and serrated on both edges ; base 

 of the adipose nearly as long as that of the rayed fin. Pectoral 

 spine a little shorter than that of the dorsal and serrated on both 

 edges. Colour silvery. 



Hob. The Andamans to the Malay Archipelago. 



24. Genus OSTEOGENIOSUS, Bleeker. 



Branchiostegals five. Gill-membranes united at the throat, 

 einarginate and overlapping the isthmus but not confluent with it; 

 upper surface of the head covered with very thin skin ; mouth 

 anterior ; upper jaw the longer. Nostrils approximating, the 

 posterior provided with a valve. Barbels, a single semi-osseous 

 maxillary pair. Teeth in the jaws villiform ; obtusely conical on 



