1849.] Catalogue of Malayan Fishes. 1353 



nasal protuberance increases with age, so does the relative length of the 

 diameter of the eye vary from 2\ times in to \ of the distance, measured 

 from the protuberance to the gill-opening. The nostrils, mouth and 

 tongue resemble those of O. lesserula. Each jaw carries a single close 

 series of from 9 to 1 1 conical teeth of a chestnut or brown colour. The 

 six central teeth of both jaws are a little larger than the rest and their 

 points become blunted with age. The armour is composed of pentagons, 

 hexagons and heptagons, with ciliated margins. Not including the 

 lateral half-series, on the back and sides appear five longitudinal ones ; 

 nine pieces from the gill-opening to the tail. The abdomen is covered 

 by nine longitudinal series of which the central one is composed of 

 12 to 14 pieces. All are closely covered with minute bony tubercles, 

 generally arranged parallel to the margins. The dorsal commences 

 opposite the anus ; the upper margin is rounded ; the third and 

 fourth ray, the longest, slightly exceed \ of the length of the head ; 

 the extent of the base is |- of the length. The anal commences oppo- 

 site the last ray of the dorsal, which it in form and length resembles. 

 The caudal is broad triangular with the posterior angles and margin 

 rounded ; the two central rays, the longest, equal the head. The pec- 

 torals are broad triangular ; the third and fourth upper rays are the long- 

 est, f of the length of the caudal. The length of the sides of the naked 

 tail is f of the caudal. Single individuals, or two or three together, 

 were observed at Pinang at long and irregular intervals. In size they 

 differed but slightly, the smallest being 6f inch in length. 



FAM. GYMNODONTIDiE. 



Gen. Diodon, Linne, 1766. 



All the teeth united into a single one in each jaw ; behind the tren- 

 chant margin of each a rounded part, transversely furrowed and form- 

 ing a powerful apparatus of mastication ; the skin armed with stout 

 spines ; no ventral fins. 



Diodon triedricus, Cuvier. 



Seba, II. XXIII. 4. 



Diodon triedricus, Cuvier : Mem. du Mus. IV. 133. 

 Diodon triedricus, Cuv. R. A. II. 367 ('). 



8l2 



