50 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



The characters selected for comparison in the various local groups 

 were the following: 



1. The number of black transverse bars or stripes across the sides 

 of the fish. 



2. The number of the same transverse bars which meet or cross 

 the lateral line. 



3. The number of round, black, dorso-lateral intermediate spots 

 situated between the transverse bars. 



4. The number of rays in the first dorsal fin. 



5. Number of fin rays in second dorsal fin. 



6. Number of dorsal finlets. 



Having thus stated the general method, it will be sufficient here 

 to state the general conclusions to which Mr. Garstang's work led. 



The American mackerel were found to constitute a distinct variety 

 or race and to differ from the European mackerel in having a greater 

 number of spots and a greater number of finlets; but it has a less 

 number of fin rays in both the first and the second dorsal fins. The 

 European mackerel were found to belong to two principal races: 

 an Irish race, and a race frequenting the English Channel and the 

 North 8ea. The Irish race again is divisible into two distinct stocks, 

 one of which belongs to the west coast of Ireland and the other to 

 the south coast of Ireland. " The Western Irish stock represents 

 more closely than any other race the primitive type of mackerel from 

 which all, whether British or American, have been derived." The 

 south Irish fish are distinctly intermediate between the west Irish 

 fish and the channel fish. These facts led Garstang to say that the 

 peculiarities which distinguish one local race from another "are 

 greatest between the races of localities which are geographically 

 remote and least between those which are geographically contiguous." 



This establishment of local races throws much light on many 

 aspects of the migration problem. The differences between the 

 American and European races show that they do not mix, and that 

 therefore no long migrations take place across the Atlantic. With 



