134 CHAEACINID.E. 



4. ICHTHYOBORUS. 



Giinther, Cat. Fishes, v. p. 362 (1864). 



Snout long and narrow, beak-like ; mouth large ; prsemaxillaries coalesced, freely 

 movable vertically, with a pair of canine teeth anteriorly, a series of small compressed 

 bicuspid teeth directed backwards on each side, and numerous minute cardiform teeth 

 on its inner surface ; maxillary bone much reduced, toothless, ankylosed to the 

 extremity of the prsemaxillary ; lower jaw toothed like the upper, but with three 

 canines in front, fitting between the two of the upper jaw; the dentary bones 

 completely united, without a trace of a suture. Cheek naked ; nostrils near the eyes, 

 on the upper surface of the snout, close together, separated by a valvular flap ; 

 gill-membranes narrowly attached to the isthmus in front; 4 branchiostegal rays. 

 Body elongate, compressed ; belly rounded. Scales small, the border strongly ciliated ; 

 lateral line equally distant from the dorsal and the ventral outlines ; a scaly process 

 at the base of the ventral fin. Dorsal fin with 15 to 17 rays, behind the vertical of 

 the ventrals ; anal with 14 to 17 rays ; a small adipose dorsal fin. 



Pectoral fin with 15 rays, ventral with 10. Tubes of the lateral line straight and 

 extending over the greater part of the exposed surface of the scale. 



No supraorbital bone ; a large fontanelle entirely separating the parietals and extending 

 forwards to between the frontals. An interorbital septum. Vertebras 47 (29 + 18). 



Air-bladder extending (on the right side) slightly beyond the body-cavity, the 

 posterior chamber three times as long as the anterior. Intestine short. 



A genus of small, Pike-like, carnivorous fishes, represented by a single species. 



1. ICHTHYOBORUS BESSE. 

 (Plate XXI. figs. 1 & 2.) 



Characinus besse, Joannis, Mag. de Zool. 1835, iv. pi. x. 



Icldliyborus microlepis, Giinther, Cat. Fish. v. p. 363 (1864), and Petherick/s Trav. ii. p. 249, pi. ii. 



fig. A (1869). 

 Ichthyborus besse, Gunther, op. cit. pp. 364, 250. 



Body strongly compressed, its depth four and one-third to five and one-fifth times 

 in the total length ; length of head three and one-third to four times. Head flattened 

 above, three to three and one-third times as long as broad ; snout pointed, a little 

 shorter than the postocular part of the head, once and a half (young) to twice as long 

 as the eye, the diameter of which is contained four and one-third (young) to six times 

 in the length of the head ; interorbital width one to one and a half diameters of the 

 eye ; upper jaw extending nearly to below the anterior border of the eye ; 17 to 20 

 teeth on each side of the upper jaw, and 14 to 16 on each side of the lower, in 

 addition to the anterior canines; width of the second suborbital two-fifths to one-half 

 that of the naked part of the cheek ; upper surface of skull rugose with fine striae. 



