116 
SCANDINAVIAN FISHES. 
fisherman chooses a different depth of water according 
to the season: as the season advances, the Mackerel 
gradually goes into deeper waiter, a fairly sure sign 
that it is on its way back to the deep sea.. 
On the west coast of Norway, according to H. 
Baars {Die Fischer eiindustrie Norwegens , Bergen 1873, 
p. 58), about 2,500 boats are engaged in this fishery, 
and the annual catch is from 30 to 35 million Macke- 
rel. The Mackerel-fishery is carried on on a still larger 
scale off the east coast of North America (see note a, 
p. 114), where the tackle employed consists chiefly of 
purse-seines". (Ekstkom, Smitt.) 
Fam XIPHIIDtE. 
Body fusiform and elongated. Eyes middle-sized. Both, the preoperculum and the supraorbital margins dentated 
during youth b , smooth {like the other bones of the head ) in full-groivn specimens. The scales vanish during growth , 
in young specimens they are ciliated and some of them platelike and spinous. During youth one continuous fin 
on the back and in the anal region, but in full-grown specimens a greater or less part of the middle of these fins 
disappears , and thus two dorsal and two anal fins are formed , the anterior being , in both cases , larger than the 
posterior. No free spinous ray in front of the anal fin. Simple, pointed conical teeth in both jaws during youth; 
but they finally disappear in quite full-grown specimens c . During youth both jaws are more or less elongated in 
a forward direction, the upper more than the lower, but in full-grown specimens the lower jaw is still more con- 
siderably shorter than the upper, which is prolonged into a “ sword ,” formed by the maxillary and intermaxillary 
bones, the vomer { rostral part) and the ethmoid bone. The superior longitudinal ridges on the skull are only 
slightly or not at all developed. In the species where there are ventral fins, they are thoracic, and the number of 
rays is less than usual, in other cases they are wanting. Gill-openings large , but the branchiostegal membranes 
partly united. Branchiostegal rays 7. Branched rays in the caudal fin at least 15. Vertebrae at least 24, more 
than 10 of them abdominal. 
Agassiz d separated this family from the Cuvierian 
Scombroids “in order more clearly to fix the characters 
of the latter;” but it is not without reason that both 
Lutken * * 6 and Lilljeborg 7 * 9 have suggested the reunion 
of these two families. It, is not only that at least one 
genus of the Scombroids (. Acanthocybium ) has the same 
retiform branchial lamellae as the Swordfishes (see above), 
nor that in the latter this coalescent formation of the 
branchial lamellae does not appear during youth 6 ', but 
also that the osteological characters, to which Agassiz 
gave the first place in his diagnosis of the Swordfishes, 
to a great extent correspond to those of the Mackerels. 
The remarkable structure in the Swordfishes of the 
haemapophyses of the caudal vertebrae, which consist of 
broad processes beneath the lateral holes of the haemal 
canal and the consequent articulation between the haemal 
a See also Materials for a History of the Mackerel Fishery b 
Comm. Fish. a. Fisher. 1881 (Washington 1884) pp. 91 — 531. 
6 In some species the corners of the temples (according to G 
strong spines, which call to mind the Trigloid type. 
c In a Swordfish which has attained a length of 8 feet we fi 
d Rech. Poiss. Foss., tome V, part. 1, pp. 1, 7 and 89. 
e Lutken, Spot. Atl., Vid. Selsk. Skr., Kbhvn., 5:te Itekke, 1 
f So. Norg. Fislcar , vol. I, p. 379, not. 1. 
9 Lutken, 1. c., p. 446. 
arches of the successive vertebrae, apparently corresponds 
to the structure of the caudal vertebrae which we have 
remarked above in Euthynnus. The strong connecting- 
links in the Swordfishes between the interspinal bones 
and also between the interhaemal, which are formed 
by the sagittal extensions of these bones, and side 
by side with which the neural and the haemal spines 
are also extraordinarily broad (extended in the same 
direction, the longitudinal direction of the body), are 
indeed wanting in the Mackerels; but still they are 
caused only by a stronger ossification of the membrane 
between these bones, which even in the Mackerels is 
sometimes fairly hard. The family character of the 
Swordfishes is thus the ensiform (sometimes cuneiform 
and terete) elongation of the snout, the chief part of 
which is composed of the rostral portion (originally 
G. Brown-Goode, J. W. Collins, R. E. Earll, and A H. Clark, Rep. 
inther, the parietal bones) and of the preoperculum are prolonged into 
id small, but numerous, teeth on the hind part of the intermaxillary bones. 
aturv. Math. Afd., vol. XII, p. 447. 
