ccciii 



392. Doryichthys Bleekeri,Day. D. 41-45, Rings 20 + 23. Malabar, 

 ascending rivers. 



Order— PLECTO GNATHI. 



Fishes with the bones of the head completely ossified, whilst those in the 

 remainder of the body are incompletely so : vertebra? few. Gill- 

 openings narrow, situated in front of the pectoral fins : gills pectinate. 

 Head generally large. Mouth narrow : the bones of the upper jaw 

 mostly united, sometimes produced into the form of a beak. Teeth 

 may be distinct in the jaws, or absent. There may be a single soft 

 dorsal appertaining to the caudal portion of the vertebral column and 

 situated opposite the anal : in some a rudimentary spinous dorsal is 

 also present : ventrals, when existing, being in the form of spines. 

 Skin smooth, with rough scales, or ossified in the form of plates or 

 spines. Air-vessel destitute of a pneumatic duct. 



Family— Gymnodontid.e. 



Bones of upper and lower jaw form a beak, having a cutting edge, and covered 

 with a layer of ivory-like substance, in which a median suture may be present 

 or absent. A soft dorsal, caudal, and anal exist, but no spinous dorsal : pectorals 

 present : ventrals absent. 



Genus — Xenopterus, Bibron. 



Chonerinus, Bleeker. 



Jaws divided by a median suture. Nostrils funnel-shaped, having 

 fringed tnargins. Dorsal and anal fins long. Body more or less covered 

 with fine dermal spines having a double or treble root. They are able to 

 inflate their bodies with air, and float on the water, abdomen uppermost . 



393. Xenopterus naritus t Richardson. D. 25-26, A. 23-25. Of a 

 yellow colour. Found throughout the Burmese rivers far above tidal 

 influence. It attains a considerable size, and is used as food. 



Genus — Tetrodon, Li 



nn. 



Bach broad or compressed into a ridge. Jaws divided by a median 

 suture. When a conspicuous nasal organ exists, there may be two on 

 either side in a papilla (Telraodon, Bleeker) : or only a single tubular 

 nasal opening on either side (Crayracion, Bleeker) : or an imperforate 

 nasal cavity with a fringed margin (body spiny) (Chelonodon, Miiller^: 

 or a simple round nasal cavity [body smooth) (Monotrelus, Bib.) ; or 

 two imperforate nasal tentacles on either side (Arothron, Mull.) : 

 or if invisible , and bach is compressed into a keel (Anosmius, Peters). 

 Dorsal and anal fins short. Body wholly or partially covered by fitie 

 dermal spines, which, however, may be entirely absent. There may be a 

 more or less distinct fold along the lower part of the tail (if nasal organs 

 are very distinct) (Gaslrophysus, MiillerJ : if there is no such fold (but 

 distinct nasal organs and spiny body) (Cheilichthys, Muller^ : or should the 

 fold be absent and the skin smooth (Liosaccus, Giinther). 



394- Tetrodon cutcutia, Ham. Buch. Teepah-benki, Ooriah. A 

 simple round nasal cavity. Body smooth. Brownish lines forming a 

 net- work on the sides of the body, whilst a large black ocellus margined 



