484 Percomorphi 
, a sword made of consolidated bones. The teeth are very feeble 
and the ventral fins reduced to two or three rays. The species 
are few in number, of large size, and very brilliant metallic 
coloration, inhabiting the warm seas, moving northward in 
summer. They are excellent as food, similar to the swordfish 
in this as in many other respects. The species are not well 
known, being too large for museum purposes, and no one having 
critically studied them in the field. Istiophorus has the dorsal 
fin very high, like a great sail, and undivided; Istiophorus n- 
gricans is rather common about the Florida Keys, where it 
reaches a length of six feet. Its great sail, blue with black 
spots, is a very striking object. Closely related to this is 
Istiophorus orientalis of Japan and other less known species 
of the East Indies. 
Tetrapturus, the spearfish, has the dorsal fin low and divided 
into two parts. Its species are taken in most warm seas, 
Tetrapturus 1mperator throughout the Atlantic, Tetrapturus am~ 
plus in Cuba, Tetrapturus mitsukurit in Japan and in Southern 
California. These much resemble swordfish in form and habits, 
and thev have been known to strike boats in the same way. 
Fossil Istiophoride are known only from fragments of the 
snout, in Europe and America, referred provisionally to Istio- 
phorus. The genus X iphiorhynchus, fossil swordfishes from the 
Eocene, known from the skull only, may be referred to this 
family, as minute teeth are present in the jaws. Xiphiorhyn- 
chus priscus is found in the London Eocene. 
The Swordfishes: Xiphiide.— The family of ‘swordfishes, 
Xiphiide, consists of a single species, Xiphias gladius, of world- 
Fic. 380.— Young Swordfish, Xiphias gladius (Linneus). (After Lutken.) : 
wide distribution in the warm seas. The snout in the sword- 
fish is still longer, more perfectly consolidated, and a still more 
effective weapon of attack. The teeth are wholly wanting, 
and there are no ventral fins, while the second of the two fins 
on the back is reduced to a slight finlet. 
