qf the Fishery Board for Scotland. 



125 



Species. 





1 



A 





2 A. 



Max. 



4v. 



Vari- 

 ants 



Min. 



Max. 



Av. 



Vari- 

 ants. 



Min. 



G. 



hiscus 



45 





40 



37 



17 



15 



45 



12 



G. 



minutus 



35 



31 



42 



28 



18 



15 5 



34 



13 



G. 



esmarkii 



31 



87*7 



71 



25 



19 



16 7 



47 



14 



The base of the first anal fin is measured from the hind edge of the 

 anus to the end of the base of the fin. 



Various relationships between the lengths of the fin-bases may be made 

 out by inspection of the averages. Take, for example, the ratio between 

 the lengths of the anal fins : — 



In luscus the first anal bears to the second anal the ratio of 40 : 15, 

 i.e., 8 : 3. 



In minutus the corresponding ratio is 31 : 15*5, i.e., 2 : 1. 



In esmarkii the corresponding ratio is 28 : 17, i.e., 5 : 3. 

 From these data, then, it might be expected that a specific character 

 could be obtained in the relation between the two anal fins. To test its 

 value from the point of view of specific description it is necessary to find 

 what ratios are found in a number of fish. These are set out below. The 

 various ratios found existing between the anal fins in respect to the length 

 of their bases is set out for each species, and the frequency with which 

 each occurred in the sample of fish is also added. 



Ratios of the 

 First Anal to 

 the Second 

 Anal Fin. 



Frequency 

 in 



G. luscus. 



Frequency 

 in 



G. minutus. 



Frequency 

 in 



G. esmarkii. 



3-3 



1 



1 







3-2 



■j 

 i 









31 





1 







3 





2 







2-9 





2 







2-8 





4 







2-7 





7 







2-6 





6 







2-5 





12 



1 





2-4 





4 







2-3 





1 



1 





2-2 





3 



4 





2-1 





1 



3 





2 







8 





19 







6 



3 



1-8 







7 



9 



17 







3 



7 



1-6 









8 



1-5 









13 



1-4 









4 



13 









2 



Total 



44 



33 



47 



