WITH SPECIAL REFERENCE TO TIIE CETACEA. 
1 7 
We are so accustomed to associate the phenomena of 
migration with Birds that we are apt to overlook the fact 
that this division of the animal kingdom has by no means 
a monopoly of these functions, and that they are shared 
to a remarkable degree by many both terrestrial and aquatic 
animals. Although the apparently trackless path of the bird 
in the air is unique of its kind, there is also to be solved the 
initial impulse which impels Anadromous fishes, as the Salmon 
family, to leave the sea for fresh water in which to propagate 
their species, and guides their offspring on their return to 
the waters in which they passed the early stages of their 
existence, or on the other hand prompts Catadromous fishes, 
like the Eel, to do precisely the reverse. We are all familiar 
with the herding together at certain seasons of vast shoals 
of Herrings, Pilchards, Sprats, or Mackerel, but we were 
not prepared for the wanderings of the common Plaice which 
have lately been revealed, and I doubt not the systematic 
investigations of the International Marine Biological research 
now proceeding will have many strange facts to acquaint us 
with, and that the wanderings of the Pleuronectidre, hitherto 
regarded as a very sedentary family, will not be found to be 
aimless. 
And this opens up a question of fresh interest — the actual 
extent of these migrations. I shall endeavour to show that 
they are much more limited than has generally been supposed 
with regard to certain marine mammals, and I doubt not 
this is also the case with the migratory fishes. I can here 
only refer you to the investigations of our President, 
Mr. Garstang, with regard to the Mackerel,* wherein he 
clearly shows that there are certain well marked races of 
this fish, which, for reasons he duly sets forth, do not intermix, 
that each race never wanders far from its normal locality, 
and that they are as truly local in their wanderings as the 
Salmon of particular rivers. Eleven years ago Mr. Stacy 
Watson, in a paper read before this Society on the “ Varieties 
* ‘J ourna l of the Plymouth Murine Biological Association,’ vol. v. Nov., 
1898, p. 235. 
VOL. VIII. 
C 
