TRANSACTIONS OF SECTION D. 513 
Two questions to be answered are the following :—-Why are eels absent 
from the Black Sea, while they are to be found in the innermost parts of the 
Baltic ? 
And why are eels present at the northern coasts of the Mexican Gulf 
and the Caribbean Sea, but absent from, or, at all events, exceedingly scarce, 
on their southern coasts ? 
Concerning the Black Sea, it is a fact, established many years ago, that 
not only this sea, but all the rivers flowing into it, ara totally devoid of 
eels. Now, the temperature of the depth, as shown by the chart, is high, 9° 
at 1000 métres ; but other factors prevent the spawning and the immigration 
from the Mediterranean, where, as a matter of fact, eels do spawn. In 
the first line spawning must be prevented by the large quantities of 
sulphuretted hydrogen found in the deep water; and, besides, the salinity 
here, without doubt, is too low, being only 22 per cent., whereas it ought to be 
at least 35°20 per cent., judging from what is the case with the Atlantic. 
Immigration of young stages from the Mediterranean must be very difficult, 
by reason of the narrow passages leading into the Black Sea; only a small 
number might be able to pass, and spreading suddenly over a large area, 
after passing, their chances to settle on the right places may be rather 
small. 
Concerning the second question, about the Mexican Gulf and the 
Caribbean Sea, we find that in both the temperature at 1000 métres depth 
is only from 4'5° to 6°. Thus it is not probable that fresh-water eels would 
be produced here ; in fact, we have no observations pointing in that direc- 
tion ; and the relatively small amount of eels yielded by the central region 
of the United States (the Mississippi region), the apparent scarcity of this 
fish in Mexico, and the total disappearance east of Tamaulipas, seem to 
exclude the possibility of any production, at all events of any large 
production. Thus, the presence of eels at the northern boundaries is most 
likely due to immigration from a centre of production lying elsewhere. 
An endeavour has been made to determine where the Western Atlantic 
eel (A. chrysypa) is found, and also to get an idea of the frequency of its 
occurrence, of its quantity or scarcity in the different localities, also in 
regard to its penetrating up into the land. 
In the southernmost part of Greenland the eel is very scarce. Its rare 
occurrence in that locality was referred to by Fabricius (1780). For 
many years we had no confirmation of his statement, but recently my 
endeavours to get a Greenland specimen were crowned with success; one 
specimen was captured and sent to the Museum of Copenhagen; it proved to 
be the Anguilla chrysypa, the American species. In Labrador it is found, 
but, apparently, not in great numbers ; in Newfoundland it seems to com- 
monly occur, since on the west coast it is caught in traps, and exported, to 
some slight extent, from this colony. It is found in great numbers in the 
eastern parts of Canada and the United States ; it also appears in numbers 
in the northern portion of Mexico and in the West Indies. 
Regarding the occurrence in the interior of the continent, statistical 
statements about the fisheries show that the number of eels—the ‘ceel- 
density,’ so to say—decreases from the sea inland. In Canada, Ontario is 
the province farthest from the Atlantic where an eel-fishery is found. In 
the United States the eastern region, north of Florida, the rivers of which 
flow into the Atlantic, shows by far the greatest density, 98 per cent. of the 
eels caught in the United States; that of the central region, west of Florida, 
where the rivers open out into the Gulf of Mexico, being very much below, 
yielding only 2 per cent. of the whole capture. 
The western region, which is drained into the Pacific, and in the main 
is lying west of the Rocky Mountains, is totally devoid of eels. 
Very interesting are the results regarding the Great Lakes; here the eel- 
fishery of Lake Ontario far exceeds that of the other lakes. A glance at 
1909 TG 
