PERC1D.E. 



numerous about the heads of fishes generally than over the 

 other parts, the viscous secretion defending the skin from the 

 action of the water. The distribution of the mucous orifices 

 over the head is one of those beautiful and advantageous pro- 

 visions of nature which are so often to be observed and ad- 

 mired. Whether the fish inhabits the stream or the lake, 

 the current of the water in the one instance, or progression 

 through it in the other, carries this defensive secretion back- 

 wards, and spreads it over the whole surface of the body. In 

 fishes with small scales, this defensive secretion is in propor- 

 tion more abundant ; and in those species which have the 

 bodies elongated, as the Eels, the mucous orifices may be 

 observed along the whole length of the lateral line. 



The formula of the number of fin-rays may be thus 

 stated : 



D. 15, 1 + 13 : P. 14 : V. 1 + 5 : A. 2 + 8 : C. 17. 



And the mode of fin-ray notation employed is thus explain- 

 ed : D. the dorsal fin, has, in the first fin, 15 rays, all spi- 

 nous ; in the second fin, 1 spinous + plus ] 3 that are soft. 

 P. pectoral fin, 14 rays, all soft. V. the ventral fin, with 



1 spinous ray -f plus 5 that are soft. A. the anal fin, with 



2 spinous rays + plus 8 that are soft. C. the tail or caudal 

 fin, 17 rays. In counting the rays of the caudal fin, those 

 only from the longest ray of the upper portion to the longest 

 ray of the lower portion, both inclusive, are enumerated. 



The Perch, though very common, is one of the most 

 beautiful of our fresh-water fishes ; and, when in good condi- 

 tion, its colours are brilliant and striking. The upper part 

 of the body is a rich greenish brown, passing into golden 

 yellowish white below ; the sides ornamented with from five 

 to seven dark transverse bands ; the irides golden yellow ; 

 the first dorsal fin brown, the membrane connecting two or 

 three of the first and last rays spotted with black ; the second 



