FAMILY, I— SILURID^. . 411 



11. Olijra. Gill-openings wide, tlie membranes not being confluent with the skin of the isthmus. Eyes 

 subcutaneous. Teeth on the palate. Barbels eight. Rayed dorsal fin with a short spine : no pectoral spine. 

 Ventral with six, anal with from fifteen to about twenty -three rays. Caudal rounded or lanceolate. Assam 

 to Pegu. 



b. A single rayed and no adipose dorsal fin. 



12. Callichrnns. Gill-openings wide, the membranes not being confluent with the skin of the isthmus. 

 Cleft of mouth does not extend to the eye. Eyes without free orbital margins. Teeth on the vomer. Barbels 

 two or four. Eayed dorsal fin when present small. A pectoral spine. Ventral with ton or less rays : anal 

 with from about forty-five to ninety-five rays. Fresh waters of India, Ceylon, Burma to the Malay Archipelago 

 and China. 



13. Wcdlago. Gill-openings wide, the membranes not being confluent with the skin of the isthmus. 

 Cleft of mouth deep, extending to behind the eyes. Eyes without free orbital margins. Teeth on the vomer. 

 Barbels four. Rayed dorsal fin short, spineless. A pectoral spine. Ventral with nine or ten rays : anal with 

 sixty -five to ninety -five rays. Fresh waters of India and Burma to the Malay Archipelago. 



14. Silurus. Gill-openings wide, the membranes not being confluent with the skin of the isthmus. 

 Eyes with free orbital margins. Teeth on the palate. Barbels four or six. Rayed dorsal fin without spine : no 

 adipose fin. Pectoral with a spine. Ventral with eight or more rays : anal with from sixty to ninety rays. 

 From eastern Europe, through Turkestan, and some of the higher Indian mountains, to the hill ranges 

 of Burma, the Malay Archipelago, China, and Japan. 



c. Two rayed hut no adipose dorsal fin. 



15. Chaca. Gill-openings narrow, the membrane being confluent with the skin of the isthmus. Mouth 

 very wide. Eyes rudimentary. No teeth on the palate. Barbels six. Dorsal and pectoral spine. Ventral 

 with six rays : anal divided into two portions. Eastern Bengal, Burma to the Malay Archipelago. 



IG. PlotuSKS. Gill-openings wide, the membranes not being confluent with the skin of the isthmus. 

 Eyes with a free orbital margin. Teeth on the palate. Barbels eight. Two rayed dorsal and anal fins : first 

 dorsal and pectoral with a spine. Ventral with about twelve rays : second dorsal and anal with numerous rays 

 and confluent with the caudal. Red Sea, east coast of Africa, seas of India to the Malay Archipelago 

 and Australia. 



B. Air-vessel more or less enclosed in bone. 



a. No adipose dorsal fin. 



17. Clarias. Gill-openings very wide, the membranes not being confluent with the skin of the isthmus 

 and separated to the chin. Eyes with a free orbital margin. Teeth on the palate. Barbels eight. A single 

 elongated rayed dorsal and anal fin : a pectoral spine. Ventral with six rays. A dendritic accessory branchial 

 appai-atus attached to some of the branchial arches. Africa and a great portion of Asia, including the Indian 

 region and the Malay Archipelago to China. 



18. Saccobranclms. Gill-ouenings very wide, the membranes not being confluent with the skin of the 

 isthmus and separated "to the chin" Eyes with a free orbital margin. Teeth on the palate. Barbels eight. A 

 short spineless dorsal fin: an elongated anal one (sixty to eighty rays). A strong pectoral spine. Ventral 

 with six rays. An elongated respiratory air-sac, extending backwards amongst the muscles of the back on 

 either side of the neural spines. Sind, India and Ceylon to Burma and Cochin China. 



b. An adipose dorsal fin. 



19. Silundia. Gill-openings very wide, the membranes not being confluent with the skin of the 

 isthmus and separated to the chin. Eyes with a broad, circular adipose lid and free orbital margin. Teeth 

 on the palate. Barbels two or four. A short dorsal fin having a spine : an elongated anal (forty or fifty rays). 

 A jiectoral spine. Ventral with six rays. India and Burma. 



20. A'ilia. Gill-openings wide, the membranes not being confluent with the skin of the isthmus. Eyes 

 with a free orbital margin. Teeth on the palate. Barbels eight. No rayed dorsal fin. Pectoral with a spine : 

 an elongated anal (sixty to seventy-five rays) : a pectoral spine. Ventral with six rays. Sind, the valley of 

 the Ganges, and Assam. 



21. AiliioJdhys. Similar to Ailia, but destitute of ventral fins. Indus and Punjab rivers, also Ganges 

 and Jumna. 



22. Eidropiiichthjs. Gill-openings very wide, the membranes not being confluent with the skin of the 

 isthmus and separated to the chin. Eyes having a broad circular adipose lid. Teeth on the palate. Barbels 

 eight. A short dorsal fin with a spine: a pectoral spine: an elongated anal fin (forty-seven to fifty rays). 

 Ventral with six rays. Large rivers of India and Burma. 



23. Amblyceps. Gill-openings wide, the membranes not being confluent with the skin of the isthmus 

 and notched to the chin. Eyes subcutaneous. No teeth on the palate. Barbels eight. Dorsal fin with one 

 spine iind six rays : a small pectoral spine. Anal rather short (eleven to twelve rays). Ventral with six rays. 

 Valley of Ganges, eastern Bengal to Burma. 



24. Sisor. Gill-openings narrow, the membranes being confluent with that of the Lsthmus. Eyes small. 

 Osseous plates along the back, the adipose fin in the form of a short spine. Teeth absent. Barbels, 

 one maxillary and several mandiljular pairs. A short dorsal fin with one spine and six rays : a pectoral 



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