■FISHES OF THE GULF OF MAINE 163 



THE HALFBEAKS. FAMILY HEMIRAMPHID^ 



The halfbeaks are close allies of the billfish (Belonidse, p. 161), but in the only 

 species of present concern the lower jaw is greatly elongate while the upper jaw is 

 short. They are herbivorous, feeding mainly on green algse, not carnivorous 

 like their relatives. There are many species in warm seas, only one of which is 

 known to reach the Gulf of Maine. 



61. Halfbeak (HyporJiamphus roberti Cuvier and Valenciennes) 



Skipjack 



Jordan and Evermann, 1896-1900, p. 721. 



Description. — The most striking feature of the halfbeak, one which is enough 

 of itself to mark it off from every other fish known from the Gulf of Maine, is the 

 fact that while the lower jaw is as long as in the silver gars, the upper is very short.*" 

 This is a slender fish, its body being only one-eighth as deep as long, tapering slightly 

 toward head and tail. As in the silver gar, its dorsal (14 to 16 rays) and anal (15 

 to 17 rays) fins are situated far back, about equal in length and similar in outline, 

 the former over the latter, without finlets. The ventrals stand about midway 



Fio. 69. — Halfbeak {Hyporhamphus roberti) 



between the eye and the base of the caudal. The teeth are small and the scales 

 largest on the upper surface of the head. In young fish the beak is much shorter 

 than it is in adults. 



Color. — Translucent bottle green with silvery tinge above, each side with a 

 narrow but well-defined silvery band running from pectoral to caudal fin, the sides 

 darkest above and paler below. The tip of the lower jaw is crimson in life, with a 

 short filament, and tlu-ee narrow dark streaks rim along the middle of the back. 

 The anterior parts of dorsal and anal and the tips of caudal fins are dusky. The 

 belly lining is black. 



Size. — Adults are seldom more than 1 foot long. 



General range. — Tropical and subtropical on both coasts of America and in the 

 Gulf of Mexico; not uncommon northward to Cape Cod, and straying to the coast 

 of Maine. Abundant ofi' the South Atlantic States. 



Occurrence in the Gulf of Maine. — In our cool boreal waters the halfbeak is 

 only a rare stray from the south, so far recorded only twice in the Gulf of 

 Maine — that is, from Machias and from Casco Bay, Me. 



8" Should a halfbeak be taken in the Gulf of Maine it would be well to consult Jordan and Evermann, for there are several 

 other species that might reach there as strays, either via the Gulf Stream route or from offshore. One, indeed iEulepiorhamphuit 

 vdoi), has been taken at Nantucket. Its lower jaw is even longer and more slender than that of the halfbeak, its body is more 

 compressed, and its pectoral fins are longer. 



