98 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Family XXI 1. ESOCIIM:. The Needle-fishes. 
Body elongate, very slender, compressed or not, covered with small thin scales. Lateral line 
very low, running as a fold alongside of belly. Both jaws produced in a beak, the lower jaw the 
longer, very much the longer in the young, which resemble Hemiramphus ; maxillaries grown fast to 
premaxillaries; each jaw with a hand of small, sharp teeth, besides a series of longer, wide-set, sharp, 
conical teeth. No linlets. Dorsal fin opposite anal, both tins rather long. Air-bladder present. 
Lower pharyngeals united to form a long, slender, narrow plate, with flat surface, covered with small, 
pointed teeth; upper pharyngeals distinct, the third pair little enlarged, each with some 15 moderate, 
unequal pointed teeth ( Tylosurus marinus); fourth pair well developed, with similar teeth, but without 
anterior processes. Vertebrae numerous, with zygapophyses. Ovary single. 
Voracious, carnivorous fishes, bearing a superficial resemblance to the gar pikes; found in all 
warm seas, sometimes entering rivers. 
This family contains 4 genera, only 2 of which (Tylosurus and Athlennes) are found in our waters, 
and only the first is represented in Porto Rico; the species are about 50, the majority of them American. 
Their habits are ordinarily much like those of the pike, but when startled they swim along the surface 
with extraordinary rapidity, often leaping above the water for short distances. When thus leaping 
the large species of the tropics are sources of danger to incautious fishermen, sometimes piercing the 
naked abdomen of the savages. Most of them are good food-fishes, but the green color of the bones 
of the larger species often causes them to be avoided, for no good reason. 
a. Gillrakers none; no teeth on vomer: dorsal and anal elevated In front; caudal fin lunate. 
b. Body subterete or slightly compressed, its breadth more than two-thirds its greatest depth Tylosurus, 33 
bb. Body much compressed, its breadth not half its greatest depth... Athlennes 
Genus 33. TYLOSURUS Cocco. The Hound-fishes. 
B< >dy elongate, very slender, not much compressed. Both jaws prolonged into a beak, lower jaw 
somewhat the longer, much the longer in young fishes, the very young resembling Hemiramplms. 
Each jaw armed with a band of small, sharp teeth, beside which is a series of longer, wide-set, sharp, 
conical, unequal teeth; no teeth on vomer or palatines. Scales small, thin; lateral line running along 
the side of the belly, becoming median on the tail. No finlets. Dorsal fin more or less elevated 
anteriorly; caudal fin short, unequally lunated or forked; pectorals moderate; ventrals small, inserted 
behind the middle of the body. Gillrakers obsolete. Bones usually more or less green. 
This genus contains numerous species of comparatively large size. Voracious fishes, chiefly Amer- 
ican, one species crossing to Europe, some of them entering rivers. 
a. Mouth capable of being nearly or quite closed, upper jaw not conspicuously arched at base. 
b. Caudal peduncle compressed, deeper than broad, without trace of keel along the lateral line; no fold of skin across 
preoperele; caudal subtruncate, the lower lobe somewhat produced; sides with a bluish-silvery band; species 
of small size, with scales and bones not green. 
c. Scales comparatively large, about 85 before the dorsal fin, and about 7 or 8 rows on the cheek; body robust, depth 
about 5 in head; coloration pale, dorsal and caudal brick-red in life; lateral stripe narrow for its entire length: 
no scapular blotch notatus 
cc. Scales small, 140 to 150 before dorsal fin, about 12 rows on the cheek; body slender; ventrals inserted at a point 
nearer cheeks than base of caudal; fins without red; lateral stripe broadened below dorsal fin. 
d. Body very slender, depth 7 in head, which is 2.83 in body; eye moderate, 2.33 to 2.75 in postorbital part of head; no 
distinct notch in the temporal ridge; maxillary not entirely concealed by preorbital. D. I, 15; A. 1 , 17; scales 
in lateral line 225 . limucu, 48 
dd. Body less slender, depth 6 in head, which is 2.9 in body; eye large, 2.2 in postorbital part of head; a distinct notch 
on temporal ridge close behind eye; maxillary almost entirely concealed by the preorbital. D. I, 15; A. I, 17; 
scales in lateral line 200 euryops 
bb. Caudal peduncle very much depressed, wider than deep, but without trace of keel. Head 2.66 in length; eye 2.5 in 
postorbital part of head; maxillary nearly concealed by preorbital; body subterete; snout very nearly twice 
length of rest of head; brownish above, silvery below, a bluish lateral stripe edged below with black and 
yellowish; scales not very small. D. 16; A. 17 diplotxnia 
bbb. Caudal peduncle more or less depressed, or at least with a more or less developed dermal keel along the lateral 
line; scales and bones more or less green. 
e. Dorsal and anal fins short, each of 14 to 18 rays, anal larger than dorsal and beginning farther forward; last rays 
of dorsal and anal low; jaws slender, about twice as long as rest of head; no fold of skin across preoperele. 
f. Eye very small, 4 to 6 in postorbital part of head; caudal keel sharp, color black; body and tail much depressed, 
microps 
