492 TELEOSTEI [CH. 



skin is naked, or as in the South American forms the body is 

 covered with large shining scutes, on the surface of which are 

 placoid denticles (Fig. 240). 



The Siluridae are nearly all fresh-water, none are found in 

 England. Amiurus, the Horned Pout, is a common North American 

 fish and is eaten. 



The HAPLOMI or Pike-like fish are characterised by possessing 

 abdominal pelvic fins and a duct of the air-bladder, but they are 

 distinguished from the Ostariophysi by having no Weberian ossicles 

 and from the Clupeiformes by the fact that the pectoral girdle has 

 no " mesocoracoid " projection. 



The maxilla usually forms part of the gape. This group of 

 normal, somewhat unspecialised fish includes the families Esocidae, 

 with Esox the well-known pike, esteemed for its flavour and dis- 

 liked for its destrucfciveness on still more valuable fish. 



FIG. 240. A Cat-fish, Amiurus catus. Diminished. From Cuvier and 

 Valenciennes. 



The group PEECESOCES, as its name implies, is transitional between 

 the sub-orders of Pike-like and Perch-like fish. The pelvic fins are 

 always behind the pectoral and never attached to the cleithrum, 

 but the air-bladder has no duct. This group includes the family 

 Mugilidae in which the pelvic bones are attached to the postcleithra. 

 The best known genus is Mugil, the Grey Mullet, one of the food-fish 

 most esteemed for its flavour. As the Mullet feed on minute 

 organisms, which are filtered from the water by strainer-like pro- 

 cesses extending from the gill-arches, they cannot be taken by bait, 

 but must be caught by drawing nets round the shoal, i.e. by seining. 



The great sub-order PERCOMORPHI or Perch-like fish are charac- 

 terised by Tate Regan as the central group of Teleostei, for not only 

 do they include a large number of families, but they seeni to have 



