Series Plectognathi 423 
and three-rooted. All are reputed poisonous, especially in the 
equatorial seas. 
In Diodon the spines are very long, the anterior ones, at 
least, movable. The common porcupine-fish, Diodon hystrix, is 
found in all seas, and often in abundance. It is a sluggish fish, 
olive and spotted with black. It reaches a length of two feet 
or more, and by its long spines it is thoroughly protected from 
all enemies. A second species, equally common, is the lesser 
porcupine-fish, Diodon holacanthus. In this species, the frontal 
spines are longer than those behind the pectoral, instead of the 
reverse, as in Dtodon hystrix. Many species of Diodon are 
recorded from the Eocene, besides numerous species from later 
deposits. One of these, as Heptadiodon heptadiodon from the 
Eocene of Italy, with the teeth subdivided, possibly represents 
a distinct family. Dziodon erinaceus is found in the Eocene of 
Monte Bolca and Progymnodon hilgendorft in the Eocene of 
Egypt. 
In the rabbit-fishes (Chilomycterus) the body is box-shaped, 
Fic. 362.—Rabbit-fish, Chilomycterus schepfi (Walbaum). Noank, Conn. 
covered with triangular spines, much shorter and broader at 
base than those of Diodon. Numerous species are known. 
Chilomycterus schepfi is the common rabbit-fish, or swell- 
toad of our Atlantic coast, light green, prettily varied with black 
lines. The larger, Chilomycterus affinis, with the pectoral fin 
spotted with black, is widely diffused through the Pacific. It 
is rather common in Japan, where it is the torabuku, or tiger 
puffer. It is found also in Hawaii, and it is once recorded by 
Dr. Eigenmann from San Pedro, California, and once by Snod- 
grass and Heller, from the Galapagos. 
