of the Fish ery Board for Scotland. 



(1) When the number of finlets varies, the number of fin-rays remains 

 normal, or varies in the opposite sense. 



(2) When the number of fin-rays varies, the number of finlets remains 

 normal, or varies in the opposite sense. 



The variation of the finlets in the opposite sense to the fin-rays is more 

 apparent than real. So long as a distinction is made between the fin- 

 rays and the finlets, the compensating variation seems to occur. But the 

 finlets are really detached rays of the second dorsal fin. Very often a 

 finlet remains attached to the fin, and occasionally a fin-ray becomes 

 detached from the fin, in which cases we get such compensating variations 

 as 13 fin-rays and 4 finlets and 11 fin-rays and 6 finlets, which of course 

 together give the normal total 12 + 5 (17). In these compensating 

 variations there is no real variation in number, simply a slight variation 

 in location. The rearrangement (in brackets) of the figures in Table X. 

 eliminates this compensating variation. The generalisation may there- 

 fore be, with great probability, simplified thus — (1) that with variations 

 in the number of finlets there are associated the normal number of fin- 

 rays ; (2) that with variations in the number of fin-rays there are associ- 

 ated the normal number of finlets. 



Table X. 



Combination of Variations in One Couple with the Normal in the other. 



Variations in Dorsal Couple. 



Variations in Anal Couple. 



2nd 

 Dorsal 

 Fin-rays. 



Dorsal 

 Finlets. 



Anal 

 Fin-rays. 



Anal 

 Finlets. 



Fre- 

 quency. 



Anal 

 Fin-rays- 



Anal 

 Finlets. 



2nd 



Dorsal 

 Fin-rays- 



Dorsal 

 Finlets. 



Fre- 

 quency. 



13 (12) 



12 



12 



11 (12) 

 12 



4(5) 



4 



4 



6(5) 

 6 



12 

 12 



11 (12) 

 10 (11) 

 12 



5 

 5 



6(5) 

 6(5) 

 6 



4 

 4 

 1 

 1 



3 



13 (12) 

 12 



14 (13) 

 13 (12) 

 13 (12) 

 11 (12) 



4(5) 

 4 



4(5) 

 4(5) 

 4(5) 

 6(5) 



12 

 12 

 12 

 11 

 13 

 12 



5 

 5 

 5 

 5 

 5 

 5 



5 

 2 

 1 

 1 

 1 

 5 



Table XI. 



Variations in the Number of 2nd Dorsal 

 Fin-rays, accompanied by Normal 

 Number of Dorsal and Anal Finlets. 



Variations in the Number of Anal Fin- 

 rays, accompanied by Normal Number 

 of Dorsal and Anal Finlets. 



2nd 

 Dorsal 

 Fin-rays. 



Dorsal 

 Finlets. 



Anal 

 Fin-rays. 



Anal 

 Finlets. 



Fre- 

 quency- 



Anal 

 Fin -rays. 



Anal 

 Finlets. 



Dorsal 

 Fin-rays. 



Dorsal 

 Finlets. 



Fre- 

 quency. 



11 



5 



12 



5 



35 



11 



5 



12 



5 



34 



12 



5 



12 



5 



337 



13 



5 



12 



5 



6 



13 



5 



12 



5 



12 



11 



5 



11 



5 



8 



14 



5 



12 



5 



1 



13 



5 



11 



5 



3 













11 



5 



13 



5 



1 













9 



5 



11 



5 



1 



