436 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
which is short, broad, and rounded; dorsal and anal fins short, similar to each other, rounded in form 
and placed posteriorly. Genera about 6; species 15. Sluggish fishes, living on the bottom among 
weeds and corals in tropical seas. When disturbed they swallow air and float belly upward on the 
water. Their capacity of inflation is very much less than that of the Tetraodontidse, from which family 
they differ chiefly, however, in the stronger armature and in having no division in the bony plate of 
either jaw. They are rarely used as food, being generally regarded as poisonous. The species are 
mostly well known in collections, the singular form having attracted the attention of travelers in the 
earliest times. 
a. Dermal ossifications mostly 2-rooted; the spines rather slender, but stiff and erectile; both jaws entire Diod on, p. 436 
aa. Dermal ossifications all or nearly all 3-rooted, each with a short, stiff, immovable spine; jaws each with^aT median 
suture Chilomyaerus, p. 438 
Genus 197. DIODON Linnaeus. 
Body robust, the belly moderately inflatable; dermal spines strong, stiff, most of them 2-rooted 
and erectile, a few 3-rooted and therefore immovable; both jaws entire; nasal tube simple, with 2 
lateral openings; pectoral broad, the margin undulate, the upper lobe longest; vertical fins rounded, 
the dorsal and anal short, posteriorly inserted, similar to each other. Tropical seas; the few species 
very widely distributed. 
Diodon Linneeus, Syst. Nat., Ed. X, 335, 1758 (hystrix). 
Paradiodon Bleeker, Atlas Ichth., V, 56, 1865 {lu/strix); name a substitute for Diodon, transferred to another genus; the first 
species mentioned by Linnseus being Diodon atinga, which was therefore taken by Bleeker as the type. 
a. Frontal spines long, usually longer than post-pectoral spines, about twice as long as eye in adult holacdnthus , p. 436 
aa. Frontal spines not longer than the post-pectoral spines. 
b. Dorsal rays 12, spines on forehead hystrix, p. 437 
bb. Dorsal rays 15; no spines on forehead nudifrons, p.438 
359. Diodon holacanthus Linnaeus. 
D. 12; A. 12. Very similar to Diodon hystrix, but with the frontal spines usually longer than the 
spines behind the pectorals, about twice as long as eye; predorsal spines not shortened, 2-rooted; 
erectile; about 14 to 17 spines in a series between snout and dorsal; post-pectoral spines not especially 
elongate, but movable; pectoral broader than long, upper lobe pointed, lower lobe rounded. Colora- 
tion much as in Diodon hystrix, but more variable, the spots fewer and larger; usually a broad black 
bar from eye to eye, continued below eye as a narrow bar; a broad bar across occiput; a black blotch 
above each pectoral; a short bar in front of dorsal, another in which the dorsal is inserted; a blotch 
behind the pectoral, and many small spots and blotches on the upper parts; fins tyith few spots, mostly 
immaculate in the young. Found in all warm seas, north to the Florida Keys, Lower California, and 
the Hawaiian Islands, its range coinciding with that of Diodon hystrix, from which it may prove to be 
not distinct. The differences are generally evident in the adult, but young individuals apparently 
intermediate are often found. Possibly they are the 2 sexes of the same species. Jordan and Snyder 
had this species from Japan and Doctor Steindachner records it from Laysan, whence he had one 
specimen. It was not seen by us among the Hawaiian Islands, but the Albatross obtained at Laysan 
Island, a single specimen, 9.25 inches long, upon which Professor Snyder has the following note: 
“The fins are immaculate; 10 or 12 small dusky spots scattered over the body; a broad, dark bar, 
interrupted in the middle, extending between the eyes; a similar bar on nape, a spot as large as eye 
above and behind pectoral, a median brown bar on back anterior to dorsal, and a blotch surrounding 
base of dorsal.” 
Diodon holocanthus Linnaeus, Syst. Nat., Ed. X, 335, 1758, India (based on Artedi; misprint for holacanthus); Snyder, Bull. 
U. S. Fish Com., XXII, 1902 (Jan. 19, 1904), 535' (Laysan Island). 
Diodon liturosus Shaw, Gen. Zool., v. 436, 2, 1804; after Le Diodon tachete LacCpOde. 
Diodon spinosissimus Cuvier, MCm. Mus. Hist. Nat., IV, 134, 1818, no locality. 
Diodon novemmaculatus Cuvier, op. cit., IV, 136, pi. 6, 1818, no locality. 
Diodon sexmaculatus Cuvier, op. cit., IV, 136, pi. 7, 1818, no locality. 
Diodon multimaculatus Cuvier, op. cit., IV, 137, 1818, no locality. 
Diodon quadrimaculatus Cuvier, op. cit., IV, 137, pi. 6, 1818, Tahiti. 
Diodon melanopsis Kaup, Weigmann’s Archiv, 1855, 228. 
