104 Part TIL — Twenty-sixth Animal Report 



pollachius, in one fish measuring 30 cm. in length the former was 

 slightly the greater, while in four specimens measuring 36-93 cm. in 

 length the first dorsal fin was the greater. 



The comparative lengths of the paired fins form a specific character of 

 some value. In each species there is a more or less extensive range of 

 variation. In some, eg., virens, the range is short; in the majority it is 

 much greater than in that species. 



During the research it Avas noticed that there might be in a species a 

 character that was specially variable, what might be termed an unstable 

 character. Thus in esmarki the relation between the lengths of the 

 pectoral and first dorsal fins was much more subject to variation than in 

 the other species. 



Fin-rays. . 



The other external characters which have been adopted for classification 

 are the numbers of rays in the unpaired fins. The rays of the paired 

 tins have not been counted except in three species, The number of rays 

 in the ventral fin was found constant at 6. The rays of the pectoral fin 

 varied in luscus and minutus from 18-20, and in esmarki from 19-20. 

 The number of specimens examined were respectively 4, 8, and 5. In 

 the caudal fin 38 and 40 rays were found in luscus, 38 and 39 in minutus, 

 and 40 in esmarki. In this character, 2, 3, and 1 specimens respectively 

 were counted. 



The number of rays in each fin is shown for each fish in the following 

 tables : — 



[Tables. 



