CCC1V 



with white exists on the side. Mouths of the Ganges, Irrawaddi, and 

 other large rivers, ascending far ahove tidal influence. 



395. Tetrodon fluviatilis, Ham. Buch. Two imperforate nasal 

 tentacles on either side. Body nearly smooth. Superiorly greenish- 

 yellow,with vermiculated blackish lines, becoming white below : there 

 are also irregular black spots and blotches. Large rivers of India and 

 Burma, far above tidal influence. 



396. Te.trodonpatoca,}$a,m. Buch. Bheng-pulli, Ooriah : Nga-boo- 

 din, Burm. An imperforate nasal cavity with a fringed margin. Body 

 spiny. Light brown above with whitish spots, becoming silvery below. 

 Large rivers of India and Burma, far above tidal reach. 



Sub-class CHONDROPTERYGII. 



Skeleton cartilaginous : no cranial sutures. Rarely a single 

 gill-opening, as the gills by their outer edges are attached 

 to the skin, and there exists an intervening gill-opening* 

 between each : no gill-cover. Three series of valves at 

 the bulbus arteries us. Optic nerves although united 

 do not decussate. Body with vertical and paired fins, 

 the posterior pair abdominal : caudal with an upper 

 lobe, which is elongated. Intestines with a spiral valve. 

 Male sex with prehensile organs attached to the vertical 

 fins. Ovaries containing large ova which are fertilised, 

 and in some likewise developed internally. Embryo with 

 external deciduous gills. No air-vessel. 



Order PL A GIOSTOMA TA. 



Body more or less cylindrical, or depressed : the trunk may or may not 

 pass into the tail. From five to seven gill-openings, which may be 

 lateral or inferior. Jaws distinct from the skull. 



Sul-OrderSELACHOlDEI, OR SHARKS. 



ody more or less cylindrical, gradually merging into the tail. 

 Gill-openings lateral. 



CARCHARIID.E. 



The snout may be produced longitudinally (Carchariinae or true sharks) : or laterally 

 (Zygsenina or hammer-headed sharks). Spiracles absent or present. Eye with 

 a nictitating meinhrane. A small pit may or may not exist above the root of the 

 tail, and a second behind the angle of the mouth may be present or absent. Mouth 

 crescentic, inferior. Teeth may be erect or oblique, with a single cusp, hav- 

 ing sharp, smooth, or serrated edges : or they may be small, the cusps being 

 obsolete : or with one in the centre, or one or two lateral ones : or even obtuse. 

 The first dorsal fin, destitute of a spine, is placed opposite the interspace between 

 the pectoral and ventral : anal fin present. 



Genus C ARC EL ARIAS, Mull, and IJenle. 



No spiracles. A pit above the root of the caudal fin. Snout longi- 

 tudinally produced. Mouth crescentic : the labial fold or groove rarely 



