SWORDFISHES. 
117 
the point of the trabecula) and the ethmoid bone which 
lies behind and within the rostral portion, while the 
point and the lateral edges of the sword are formed 
by the intermaxillary bones. The other differences 
between the Swordfishes and the Scombroids are the 
round shape of both nostrils and the greater distance 
between the posterior nostril and the eye in the former 
— in which respect the Xiphiidce come nearer the 
Horse-Mackerels — the smaller size of the subopercu- 
lum and interoperculum - — the operculum, however, is 
larger in the Swordfishes — and the smooth, or only 
slightly rugose, anterior edges of the branchial arches, 
where strongly developed gill-rakers appear in the Mac- 
kerels. The greatest systematic importance of the fa- 
mily Xiphiidce consists in the changes due to age which 
have been given by Gunther" and Lutken 6 and partly 
even by Cuvier c , and which we have therefore given 
in the above diagnosis of the family. First we see the 
larval stage (fig. 32), with the large eyes; the low, 
continuous dorsal bn and the similar, but smaller, anal 
bn; the rounded caudal bn; the broad and short pec- 
toral bus, which are still set fairly high; and the spi- 
nous equipment of the head, which reminds us of the 
Trigloid type or the juvenile forms of the Berycidce d . 
When the snout and the lower jaw (the length of which, 
however, is soon reduced again) begin to grow elong- 
ated, and the spinous equipment of the head to vanish, 
there appear other traits of older piscine forms, several 
scaly formations on the body (hg. 33), rows of spinous 
plates and scales, one on each side of the bases of the 
dorsal and anal bus and others, parallel to each other, 
on the sides, while in the intervals between these rows 
we bnd small scales, which also cover the head and 
snout, also spinous or ciliated. These scaly formations 
are not imbricate, but juxtaposed. During this period 
there are also fairly strong jaw-teeth; the unpaired bus 
appear as before; the body is long and slender; the 
caudal bn becomes more and more concave and is also 
prolonged and pointed like the pectoral bus; and the 
ventral bns, in those species where they are found, 
appear in the form of small protuberances, which be- 
come elongated and develop one or three rays, some- 
times longer than those of the pectoral bns. We may 
also see before long, on each side of the tail, the middle 
carina (in Xipliias) or the two small carinae (in Tetrap- 
turus and Histiopl torus ), to which we have above seen 
corresponding formations in the Scombroids. The sub- 
sequent changes are mostly reductions: the disappear- 
ance of the scaly formations, the more or less complete 
disappearance of the jaw-teeth), the reduction of the 
middle part of the dorsal and anal bns, the relative 
diminution of the eyes and, lastly, the removal of the 
Fig. 32. Young specimen of a terete-snouted species of Swordfish 
( Histiophorus ? or Tetr upturns?) from the South Atlantic. 
Magnified 7 diam. After Lutken. 
pectoral bns down towards the ventral edge, “so far,’ 
says Cuvier of Xipliias, “that at the brst glance one 
might be tempted to regard them as the ventral bns.” 
In all these changes the Swordbsh proper advances 
furthest: its relations to the other ttvo genera of the 
family (each containing two or three species) form a 
distinct chain of development, Histiophorus having three 
Fig. 33. Young Swordfish ( Xipliias gladius ) from the Atlantic. 
Magnified 2 1 /„ diam. After Lutken. 
rays in the ventral bns, Tetrapturus two and Xipliias 
having no ventral bns at all. 
This family, like the greater part of the preceding 
one, consists of distinctly pelagic hshes and powerful 
swimmers, which generally keep to the surface — those 
Avhich retain the high dorsal bn are even said to use 
it as a sail — but are also able to descend to con- 
siderable depths. They real ly belong to the Tropics 
and the warmer parts of the Temperate Zones, but some- 
times rove north into our latitudes. 
“ Journ. Mus. GodefEr., Heft. 2, p. 170; Heft. 3, p. 265; Introd. Study Fish., pp. 173—175; Handb. Ichth., pp. 117 and 118. 
b Spot. Atl., 1. c., pp. 441 etc., tab. II, fig. 10 and 11. 
c Cuv., Val., Hist. Nat. Poiss., vol. VIII, p. 261, tab. 225 et 226. 
d According to Lutken (1. c., p. 447), however, the long temporal and opercular spines are wanting in the larvae of Xipliias. 
