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forming two angles, one pointing forwards, the other backwards, the fourth 

 branchial arch having an accessory respiratory organ. Teeth absent. A 

 single-rayed dorsal fin, having the posterior ray prolonged in some species: 

 ventrals in front of or below dorsal fin : anal posterior to the dorsal, elongated : 

 caudal forked. 



379. Chatoessus modestus, Day. D. 16, A. 28, L. 1. 47, L. tr. 17. 

 Last dorsal ray not prolonged. Uniform colour. Scales regularly ar- 

 ranged. Irrawaddi and its branches, to 51 inches in length. 



380. Chatoessus manviina, Ham. Bueh. Mackundi, Ooriah. D. 14, 

 A. 21-24, L. 1. 58-60, L. tr. 22. Large rivers and tanks of Assam, 

 Orissa and Gangetic Provinces, attaining 8 inches in length. 



B. Abdomen without a serrated edge. 



Genus — Megalofs, (Commers) , Lacep. 



Branchiostegals numerous : pseudobranchia absent. Body oblong, 

 compressed. Abdomen rounded. Snout obtusely conical. Mouth anterior, 

 lower jatv prominent. A narrow osseous lamella adherent to the symphysis 

 of the mandibles, covering the intermediate part, between the two bones. 

 Gill-membranes separated. Villiform teeth on the jaws, vomer , palatine and 

 pterygoid bones, likewise on the tongue and on the base of the skull. A 

 single dorsal opposite the ventrals. 



381. Megalops cyprinoides, Brouss. Cunnay, Mai, : Punnikowu and 

 Naharm, Ooriah : Nga-tan-youet, Burm. D. 18-20, A. 24-27, L. 1. 37-42, 

 L. tr 6/6. Throughout tanks along the coasts of India and Burma. 



Family — Notopteeimi. 



Pseudobranchise absent. Body compressed. Tail prolonged, tapering. Margin of the 

 upper jaw formed by the inter-maxillaries mesially, and the maxillaries laterally. 

 Barbels absent. Opercular apparatus incomplete. A parieto-mastoid cavity on 

 either side, leading into the interior of the skull. A single-rayed dorsal fin, 

 belonging to the caudal portion of the vertebral column : anal veiy long. Head 

 and body scaled. Stomach without blind sac : two pyloric appendages. Air- 

 vessel present, and divided in its interior. The ova fall into the cavity of the 

 abdomen before exclusion. 



Genres — Notopterus, (Lacep.), Cuv. fy Val. 



Mystus, sp. Ham. Bueh. 



Branchiostegals from three to nine. Gill-membranes partly united. 

 Snout obtuse, convex. Muciferous channels on head well developed. Cleft 

 of mouth lateral, not deep. Maxilla formed of a single bone', and articulated 

 to the inter -maxillary. Loioer margin of pre-opercle serrated, likewise some of 

 the other bones of the head. Sub-opercle absent. Teeth in both jaws of 

 irregular sizes, also on vomer , palatines , pterygoid, and sphenoid bones, and 

 in two rows on the tongue. A dorsal rfn present (Notopterus) , or absent 

 (Xenomystus) : anal fin long, united to the caudal. Ventrals, when present, 

 rudimentary and united together. Scales small. Abdomen serrated along 

 its margin. Lateral line distinct. Muciferous channels on head well 

 developed. Air-vessel sub-divided internally, and ending in front in two 

 horns, the anterior of which is in immediate connection with the auditory 

 organs : posteriorly it ends in two branches divided from one another by the 

 hcemal spines. Intestines short. Cacal pylori long. 



