SILURID.E. 11 



Sixth Subfamily. 



SILUBIDJE PKOTEROPODES. 



The rayed dorsal fin is always present, and rather short ; ven- 

 trals below or in front of the dorsal. Gill-membranes confluent 

 with the skin of the isthmus. Vent before, or not much behind, 

 the middle of the length of the body. 



Group N. Hypostomatina. 



Anterior and posterior nostrils close together, generally with a flap 

 between them. Lower lip reverted and dilated. 



a. Head and body entirely covered with soft skin ; maxillary barbels only : 



South A merican . 



Adipose fin low, elongate 88. Auges, p. 222. 



Adipose fin short, with a moveable spine... 89. Stygogenes, p. 223. 



Adipose fin none, ventrals present 90. Bkontes, p. 224. 



Adipose and ventral fins absent 91 . Astroblepus, p. 224. 



b. Body completely cttirassed: South American. 



* Two barbels at each angle of the mouth. 

 Adipose fin short, with a moveable spine ... 92. Callichthys, p. 225. 



** Body with four or five longitudinal series of scutes on each side ; tail 

 rounded or compressed. 

 Adipose fin present, with a short spine ; eight dorsal rays ; interoperculum with- 

 out erectile armature 93. Plecostomus, p. 230. 



Adipose fin present, with a short spine ; from 13-14 dorsal rays ; interoperculum 

 without armature 94. Liposakcus, p. 238. 



Adipose fin present, with a short spine ; from 8 T 10 dorsal rays ; interoperculum 

 with erectile spines 95. Ch^etostomus, p. 240. 



Adipose fin present, with a short spine ; from 12-14 dorsal rays ; interoperculum 



with erectile spines 96. Pterygoplichthys, p. 251. 



Adipose fin none ; interoperculum without armature. 



97. Rhinelepis, p. 252. 

 Adipose fin none ; interoperculum with erectile spines. 



98. Acanthicus, p. 253. 



*** Tail long and depressed. 



Snout produced and spatulate 99. Loricaria, p. 254. 



Snout very long and narrow 100. Acestra, p. 260. 



c. Head partly osseous and rough ; body naked or with bony plates on the back : 



East Indian. 



No adipose fin 101. Sisor, p. 262. 



Adipose fin present 102. Erethistes, p. 263. 



d. Head and body covered with skin ; a pair of nasal barbels : East Indian. 

 A plaited adhesive apparatus between the pectorals. 



103. Pseudecheneis, p. 264. 

 Lower lip very broad, reflected 104. Exostoma, p. 264. 



