FISHES OF HAWAIIAN ISLANDS. 
119 
Family XXXIX. SYNGN AT H 1 1 >7E. — The Pipe-Fishes. 
Body elongate, usually slender, covered with bony plates which are firmly connected, forming a 
bony carapace; head slender, the snout long, tube-like, bearing the short toothless jaws at the end; 
gill-opening reduced to a small aperture behind the upper part of the opercle; tail long, prehensile or 
not, usually provided with a small caudal fin; male fishes with an egg-pouch usually placed on the 
under side of the tail, sometimes on the abdomen, commonly formed of 2 folds of skin which meet 
on the median line; the eggs are received into this pouch and retained until some time after hatching, 
when the pouch opens, permitting the young to escape; dorsal fin single, nearly median, of soft rays 
only; pectorals small or wanting; ventrals none; anal fin minute, usually present. Genera about 15; 
species 150. Small fishes, found in all warm seas, sometimes entering fresh waters. 
a. Hippocampinx: Tail prehensile; caudal fin small; head placed at a large angle with axis of body. . . Hippocampus , p. 119 
aa. Syngnathinse: Tail not prehensile, usually with a caudal fin; axis of head usually in line with axis of body. 
b. Egg-pouch of male on body; dorsal with 25 rays; rings 18+14 ... Doryrhcimphus, p. 120 
bb. Egg-pouch of male on tail; dorsal with 22 rays; rings 16+36 Ichthyocampus, p. 121 
Genus 66. HIPPOCAMPUS Rafinesque. The Sea-Horses. 
Body strongly compressed, the belly gibbous, tapering abruptly to a long, quadrangular, prehen- 
sile tail; head with a distinct curved neck, placed nearly at a right angle with the direction of the 
body, surmounted by a compressed occipital crest, on the top of which is an angular, star-shaped 
coronet; top and sides of the head with spines; physiognomy remarkably horse-like, like that of a 
conventional “knight” at chess; body and tail covered with bony plates, forming rings, those on the 
body each with 6 spines or tubercles, those of the tail with 4 ; pectoral fins present, short and broad ; anal 
minute, usually present; dorsal fin moderate, opposite the vent; egg-pouch in male a sac at base of 
the tail, terminating near the vent. Species numerous, in all warm seas. These fishes attach them- 
selves by their tails to seaweed and other floating substances, and are often carried to great distances 
by currents. 
Hippocampus Rafinesque, Indice d’lttiologia Siciliana, 37, 1810 ( heptagonus=hippocampus ). 
Hippocampus Leach, Zool. Misc., 103, 1814 (hippocampus). 
a. Eye small, 4 in snout; a short keel in front of coronet hilonis , p. 119 
aa. Eye larger, 2.8 in snout; no keel before coronet .fisheri, p. 119 
79. Hippocampus hilonis Jordan & Evermann. Plate 23. 
Eye about 4 in snout; snout 2 in head; D. 16, on 3 rings; rings 12 -j- 35. Tail a little longer than 
head and trunk; trunk rather deep, compressed, its width 2 in depth; eye small, equal to interorbital 
width, which is concave, broader posteriorly; gill-opening high, rather large; spines on head and body 
very blunt, rounded or obsolete, though forming knobs of more or less equal size along tail; coronet 
with rounded knobs, before which is a short keel or trenchant ridge; base of dorsal about 1.35 in snout. 
Color in alcohol, dark or blackish brown, more or less uniform. 
This species is known to us only from the example described above. It is closely related to the 
Japanese Hippocampus aterrimus Jordan & Snyder, but on comparison with the type of that species, 
was found to differ in the presence of the keel on the top of the head and in other minor characters. 
It is also close to H. ringens. 
Hippocampus Aiionis- Jordan & Evermann, Bull. U. S. Fish Comm., XXII, 1902 (April 11, 1903) , 169, Hilo. (Type, No. 50626, 
U. S. Nat. Mus. Coll. A. M. Wilson.) 
80. Hippocampus fisheri Jordan & Evermann. Fig. 36. 
Eye 2.8 in snout; snout 2 in head; D. 18, on 4 rings; A. 4; P. 15; rings 12-)-34. 
Tail longer than head and trunk; trunk rather deep, compressed, its width 1.7 in depth; eye 
small, equal to interorbital width; interorbital Space concave; gill-opening small, high; spines on head 
and body rather high, sharp; 2 rings on trunk between each pair of larger spines; tail with 3 rings 
between each pair of larger spines; coronet well developed, with 5 spines; spines over eye blunt; base 
of dorsal about equal to snout; anal small, long; pectoral broad, rays rather long. 
