CLASS IY. PISCES. 



[NoTE. In the following list of the fish found in the 

 waters of Scandinavia, Denmark, and Finland, the arrange- 

 ment, ray formulas, and colour, is strictly after Nilsson.] 



I. OSTEROPTERYGIL 



Skeleton bony. 



ACANTHOPTERYGIL 



All the fin rays single, without joints. The first portion 

 of the dorsal fin, or the whole, when two are present, with 

 spinous rays ; and also the anals and the ventrals, with one 

 or more of the anterior rays spiny. The rays on the first 

 dorsal whole, single, generally sharp. 



Fam. 1. 



Cheeks soft; margins of the opercle and preopercle 

 (generally both) serrated, or armed with spines ; jaws and 

 vomer with teeth. The anterior rays of the anal fin spiny, 

 and generally one spine in each ventral. 



1. Ventrals under the Pectorals. . Two dorsals. 

 Gen. Perca, L. 



Body oblong ; back arched ; scales large and hard ; 

 opercle armed with a single spine ; preopercle dentate ; 

 opercle without scales ; tongue without teeth. 



1. PEECA FLUVIATILIS, L. Abborre. The Perch. D. F. 



Common in all the Scandinavian waters, at least as 

 far up as 69 north lat. Varies much in colour, depen- 

 dent on the water ; but the five dusky transverse bands 



