242 AMERICAN FISHES. 
of the water in those localities and at that depth is sure to be less than 
40° Fahr. How is this fact to be reconciled with the known habits of the 
fish, that it prefers the warmest weather of summer and swims at the sur- 
face in water-of temperature ranging from 55° to 70°, sinking when cool 
winds blow below? The case seemed clear enough until the inconvenient 
discovery was made, that Sword-fish are taken on bottom trawl-lines. In 
other respects their habits agree closely with those of the mackerel tribe, 
all the members of which seem sensitive to slight changes in temperature, 
and which, as a rule, prefer temperature in the neighborhood of 50° or 
more. 
The appearance of the fish at the surface depends apparently upon tem- 
perature. They are seen only upon quiet summer days, in the morning 
before ten or eleven o’clock, and in the afternoon about four o’clock. 
Old fishermen say that they rise when the mackerel rise, and when the 
mackerel go down they go down also. 
Regarding the winter abode of the Sword-fish, conjecture is useless. I 
have already discussed this question at length with reference to the men- 
haden and mackerel. With the Sword-fish the conditions are very 
different. The former are known to spawn in our waters, and the schools 
of young ones follow the old ones in toward the shores. The latter do not 
spawn in our waters. We cannot well believe that they hibernate, nor is 
the hypothesis of a sojourn in the middle strata of mid-ocean exactly 
tenable. Perhaps they migrate to some distant region, where they spawn. 
But then the spawning time of this species in the Mediterranean, as is 
related in a subsequent paragraph, appears to occur in the summer months, 
at the very time when Sword-fish are most abundant in our own waters, 
apparently feeling no responsibility for the perpetuation of their species. 
The Sword-fish, when swimming at the surface, usually allows its dorsal 
fin and the upper lobe of its caudal fin to be visible, projecting out of the 
water several inches. It is this habit which enables the fisherman to 
detect the presence of the fish. It swims slowly along, and the fishing 
schooner with a light breeze finds no difficulty in overtaking it. When 
excited its motions are very rapid and nervous. Sword-fish are sometimes 
seen to leap entirely out of the water. Early writers attributed this habit 
to the tormenting presence of parasites, but this theory seems hardly 
necessary, knowing what we do of its violent exertions at other times. 
The pointed head, the fins of the back and abdomen snugly fitting into 
