134 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
92. Exonautes gilberti Snyder. Plate 24. 
Head, to end of opercular flap, 4.6 in length; depth 7; width of body at base of pectorals 7; depth 
of caudal peduncle 3.6 in head; eye 3; snout 3.6; interorbital space 2.6; 1). 10; A. 10; scales in lateral 
series beginning above base of pectoral 48; between occiput and base of dorsal 32; between lateral 
line and dorsal 6. 
As indicated by the above measurements of the body, this is one of the most slender of the flying 
fishes. Body quadrangular in section; back broader than belly, convex; some of the median scales of 
back with low keels; interorbital space concave; snout a little shorter than diameter of eye; lower jaw 
slightly projecting beyond upper; maxillary extending to posterior border of nostril. No teeth on 
tongue or roof of mouth, those on jaws scarcely perceptible; gillrakers on first arch 25, long and 
slender; lateral line disappearing near end of anal fin. 
The pectoral fin extends to within about an eye’s diameter of base of caudal; has 18 rays, first and 
second simple; second a third of its length longer than first, which is 3.81 times diameter of eye; 
third ray divided near tip of first; tip of tin formed by branches of fourth ray, those of fifth being 
slightly shorter; second ray of dorsal fin longest, 2 in head; base of fin equal to 2 times diameter 
of eye; anal inserted the width of a scale posterior to dorsal, its base shorter than that of dorsal by 
an amount equal to the space between 2 rays; height of first and second rays about equal to that of 
fourth dorsal; ventrals inserted midway between base of caudal and a point anterior to the edge of 
operele, a distance equal to diameter of pupil; extending posteriorly a little beyond the base of anal, 
not beyond tip of last ray when depressed; upper lobe of caudal pointed, its length 3 times the width 
of the interorbital space; lower lobe an eye’s diameter longer. 
Color in alcohol, dark brown above, silvery below; pectoral without spots, dusky, the free edge 
with a white area as wide as pupil, proximal to which is a blackish band two-thirds as wide as the eye; 
upper or anterior edge of fin light, an indistinct dark area extending along the first to fourth rays; 
lower or posterior edge of fin along the last 4 rays white; middle rays of ventrals dusky, the fin 
indistinctly bordered with white; free edge of caudal bordered with white; dorsal dusky; anal white. 
In life, steel-blue above, silvery below. 
This species is apparently related to Exonautes rondeletii (Cuv. & Val. ) of the Atlantic. The type 
(No. 50872, U. S. N. M.) is the only specimen known. It is 10.43 inches long (snout to end of lower 
caudal lobe). It came aboard the Albatross at night near 28° 30' N. and 140° W. 
Exonautes gilberti Snyder, Bull. U. S. Fish Comm., XXII, 1902 (Jan. 19, 1904), 522, pi. 7, tig. 13, northeast of Honolulu 
between Albatross stations 3799 and 3800 . 
Genus 79. CYPSILURUS Swainson. 
Body elongate, broad above, somewhat compressed; head short, blunt, narrowed below; mouth 
small; jaws very short, about equal; chin without barbel; maxillaries not joined to the premaxillaries; 
teeth very feeble or wanting; eyes large; gillrakers moderate; scales large, deciduous; no finlets; 
dorsal fin short, opposite anal, which is considerably shorter than dorsal; caudal widely forked, the 
lower lobe the longer; pectoral fins very long, reaching past the beginning of anal, and serving as 
organs of flight, their great size enabling the fishes to sustain themselves in the air for some time; 
ventral fins large, posteriorly inserted, also used as organs of flight ; air-bladder very large; no pyloric 
coeca. Species numerous, in all warm seas, living mostly in the open water and swimming in large 
schools. The species are largely cosmopolitan, differing from Exonautes in the much shorter anal. 
Cypsilurus Swainson, Class. Fish., II, 296, 1839 (nuttalli). 
a. Dorsal 12; anal S; scales 43; dorsal plain.-... simus, p. 134 
aa. Dorsal 14; anal 11; scales SO; dorsal black above. bahiensis , p. 136 
aaa. Dorsal 16; anal 10; scales 60; dorsal with a large dark spot. atrisignis, p. 136 
93. Cypsilurus simus (Cuvier & Valenciennes). “ Malolo." Fig. 46. 
Head 4 in length; depth 4.67; I). 12; A. 8; P. 15; V. 6; scales 43 to base of caudal; 12 scales in a 
transverse series to middle of belly; greatest width of head about 1.2 in its depth; snout 4.67 in head; 
eye 3.2, 1.3 in postocular part of head, 1.4 in interorbital space; depth of caudal peduncle about 3 in 
head; base of dorsal 5 in body; base of anal 3 in head; ventral about 3.6 in body. 
