CAT -FISHES, 559 



have to be mentioned : Soleotalpa and Apio7iichthys, Soles 

 with rudimentary eyes ; Ammopleurops, A2Jhoristia, and 

 Plagusia, wliich are closely allied to Cynoglossus, the latter 

 genus having the lips provided with tentacles. 



FOURTH ORDER— PHYSOSTOMI. 



All the fin-rays articulated, only the first of the dorsal and 

 pectoral fins is sometimes ossified. Ventral fins, if present, 

 abdominal, luithout spine. Air-Uadder, if present, tvith apneu- 

 matic duct {except in Scomhresocidce). 



FiEST Family — Silurid^. 



Skin naked or with osseous scutes, hut without scales. 

 Barhels always present ; maxillary ho7ie rudimentary, almost 

 always forming a support to a maxillary harbel. 3fargin of 

 the upper jaio formed hy the intermaxillaries only. Suhoper- 

 cidum absent. Air-bladder generally present, communicating 

 loith the organ of hearing by means of the auditory ossicles. 

 Adip)ose fin present or absent. 



A large family, represented by numerous genera, which 

 exhibit a great variety of form and structure of the fins ; they 

 inhabit the fresh waters of all the temperate and tropical 

 regions ; a few enter the sea but keep near the coast. The 

 first appearance of Siluroids is indicated by some fossil remains 

 in tertiary deposits of the highlands of Padang in Sumatra, 

 where Pseudeutropius and Bagarius, types well represented in 

 the living Indian fauna, have been found. Also in North 

 America spines referable to Cat-fishes have been found in 

 tertiary formations. 



The skeleton of the typical Siluroids shows many peculia- 

 rities. The cranial cavity is not membranous on the sides. 



