186 TELEOSTEI. PHYSOSTOMI. 



Upper caudal lobe the longer. Colour purplish superiorly, 

 becoming dull white beneath ; fins externally stained with grey or 

 black, and a blackish spot on the adipose dorsal. Air-bladder 

 large and somewhat heart-shaped. On removing its lower wall a 

 longitudinal septum is seen in its posterior half but not anteriorly. 

 It has three transverse subdivisions, forming it into five chambers, 

 the anterior of which is nearly half the size of the entire organ, 

 and has no longitudinal septum. The four lateral chambers com- 

 municate freely with each other on both sides, also anteriorly with 

 the large chamber. 



Hob. Seas, estuaries, and tidal rivers of Orissa and Bengal to 

 Siam. It attains \\ feet (or according to Hamilton Buchanan 

 3 feet) or more in length ; it is commonly seen about 8 or 10 inches 

 long. 



198. (20.) Ariusjatms. 



P. 1 



4 (see synon.). 



Pimelodus jatius, Ham. Buck. Fish. Ganyes, pp. 171, 370. 

 Arius jatius, Day, Fish. India, p. 400, pi. cvi, tig. 



Nga-youn and Nya-yeh, Burmese. 

 B. vi. D. 1/7 | 0. P. 1/10. V. 6. A. 18 (5/13). C. 17. 



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

 length. Eyes diameter 4| to 5 in the length of head, 1| diameters 

 from the end of snout, and 1 J to 2 apart. Height of head nearly 

 equal to its width, the latter equal to its length excluding 

 the snout. Upper ja\v the longer ; the extent of the gape 

 of the mouth equals one third of the length of the head. 

 Summit of the posterior portion of the head sparingly granulated, 

 the occipital process more thickly so. The median longitudinal 

 groove on the head narrow, and continued almost to the base of the 

 occipital process, which latter is keeled, as wide at its base as long, 

 and reaches the narrow V-shaped basal bone of the dorsal fin. 

 Opercle wider than high. Barbels short, the maxillary pair 

 shorter than the head, the outer mandibular pair just reach the 

 gill-opening. Teeth villiform, in a band six times as long as wide 

 in the premaxillaries ; on the palate globular,' in a small oval patch 

 posteriorly, scarcely exceeding half the diameter of the eye ; they 

 may be entirely absent. Fins dorsal as high as the body ; dorsal 

 spine strong, as long as the head excluding the snout, serrated on 

 both sides ; the base of the adipose dorsal four fifths of that of the 

 rayed fin. Pectoral spine as long as that of the dorsal, serrated 

 externally, denticulated internally, reaching as far as the ventral 

 fin. The latter extends to the anal. Colmir dark bluish along 

 the back, becoming lighter on the sides and beneath. Fins yellowish, 

 lower half of dorsal stained with grey. Upper edge deep black. 

 A deep black spot on the upper half of the adipose fin; caudal' 

 edged with black, and anal with a dark spot on its edge near the 

 middle. 



Hab, Estuaries and rivers of Bengal and Burma, ascending far 

 above tidal reach, and attaining a foot or more in length. 



