84 FISHES. 



20. Perca. Jaws r unequal : teeth sharp, incurved: gill' 

 membrane T-rayed ; the covers scaly, of 3 pieces, the 

 upper-piece serrate: lateral-line arched with the 

 hack : scales mostly hard and rough : dorsal-fin spi- 

 nous on the fore-part : vent nearer the head than the 

 tail. 



21. Scomber. Head compressed, smooth: body oblong, 

 smooth, sometimes carinate by the lateral line : gill- 

 membrane 1 -rayed ; between the dorsal-fin and tail are 

 mostly several spurious fins. 



22. Gasterosteus. Jaws armed with minute teeth : 

 gill-membrane 3, 6, or T-rayed; the cover of 2 pieces, 

 rounded and striate ; body somewhat lengthened : 

 lateral-line straight : dorsal-Jin single, with distinct 

 spines between it aad the head : ventral-fins spinous : 

 belly carinate or shielded on the sides, and bonj 

 beneath. 



23. Mullus, Head compressed, sloping, scaly: eyes 

 oblong, approximate, vertical, furnished with a nicti- 

 tant membrane : nostrils double, minute : palate armed 

 with small teeth : month bearded : gill-membrane 

 3- rayed ; the covers of 3 pieces, very finely striate : 

 body clothed with large deciduous scales. 



24. Trigla. Head large, mailed, marked with rough 

 lines: eyes large, round, vertical: palate and jaws 

 armed with sharp teeth : gill-membrane 7 -rayed; 

 the cover of a single radiate spinous piece : back 

 straight, with a longitudinal spinous groove each 

 side : pectoral-fins with generally finger-shaped pro- 

 cesses placed before them. 



ORDER IV. ABDOMINALES. 



Bony fishes , with the ventral fins placed behind the pectoral. 



25. Cobitis. Head small, oblong, naked : mouth gene- 

 rally bearded : eyes seated in the upper-part of the 

 head i gill-membrane 4-6-rayed : the covers of one 

 piece, closing beneath : body of nearly equal thick- 

 ness from head to tail, covered with mucus and small 

 thin easily deciduous scales : back straight, with a 

 single fin : 'vent nearer the tail : tail rounded. 



26. Salmo. Head smooth, compressed : tongue cartila- 

 ginous, moveable :. teeth in the jaws and on the tongue: 

 gill-membrane 4-l2-rayed ; the cover of 3 pieces : 

 body compressed : back convex, furnished on the 

 hind-part with a fleshy fin without rays : lateral-line 

 straight, nearer the back. 



