98 NOTES AND COMMENTS [February 



of the first dorsal fin the variation is greater, but here the difficulty of 

 accurately determining in all instances the exact number of fin-rays 

 present (owing to the extreme minuteness of the posterior rays) has 

 also provided an obstacle to very definite results. Nevertheless 

 Mr. Garstang comes to tin's " paramount conclusion " : — That the 

 mackerel which frequent British waters are not exactly alike in all 

 localities, but possess certain average peculiarities which distinguish 

 one local race from another. These peculiarities are greatest between 

 the races of localities which are geographically remote, and least 

 between those which occupy areas that are geographically contiguous. 

 Between the mackerel of the North Sea and English Channel there 

 are no differences at all ; but the Irish race is distinctly divisible into 

 two stocks, one of which is restricted to the west coast, the other to 

 the south. A considerable amount of mixture takes place between 

 the southern Irish stock and the fish which frequent the mouth of the 

 English Channel. 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. 



If these results be accepted or confirmed, the problems of the 

 migrations of the mackerel and of its winter home are considerably 

 simplified. The Irish fish in winter must remain off their own coasts, 

 or they would lose their peculiarities by mixture with other races. 

 The North Sea and Channel fish probably have the same winter haunts 

 off the mouth of the English Channel — not too far to the westward, or 

 they would mix with the Irish fish. That the North Sea fish migrate 

 into the Channel in winter is rendered probable by the enormous con- 

 centration of mackerel in the southern part of the North Sea in autumn, 

 and by the prolongation of the mackerel fishery far into the winter off 

 the Devon and Cornish coasts of the Channel, long after the fish have 

 disappeared from the North Sea and the Irish coasts alike. 



The paper is one of the highest importance to both systematists 

 and practical fishermen. 



The Plymouth Laboratory. 



Othek papers contained in the same number of the Journal of the 

 Marine Biological Association are: — "Report on Trawling in Bays on the 

 South Coast of Devon," by E. W. L. Holt, with an Appendix by F. B. 

 Stead. " Notes on Pontobdella muricata, the Skate-leech," by Hon. 

 Henry Gibbs. " Notes on the Reproduction of Teleostean Fishes in 

 the South-Western District," by E. W. L. Holt and L. W. Byrne. 

 " The Great Silver Smelt, Argentina silus, Nilss. An addition to the 

 List of British Fishes," by E. W. L. Holt, who gives the correct locality 

 as 50° 20' N. and 8° 25' W., or about 75 miles true S. of the Old Head 

 of Kinsale; depth 74 fathoms. This sensibly extends the range of 



