Series Plectognathi 629 
immaculatus, the common species of Japan, is without spines; 
Ostracion sebe of Hawaii and Samoa is deep, rich blue with 
spots of golden. Aracana is also of East Indian origin; Ara- 
cana aculeata, with numerous species, is common in Japan. 
Fic. 523——Hornless Trunkfish, Lactophrys trigonus (Linneus). Tortugas, Fla. 
A fossil species of Ostracion (O. micrurum) is known from the 
Eocene of Monte Bolca. 
The Gymnodontes.— The group of Gymnodontes, having the 
teeth united in a turtle-like beak, carry still further the degen- 
Ua wy 
Fic. 524.—Skeleton of the Cowfish, Lactophrys tricornis (Linnzus). 
eration of scales and fins. There is no trace of spinous dorsal, 
or ventral. The scales are reduced to thorns or prickles, or 
are lost altogether. All the species have the habit of inflating 
themselves with air when disturbed, thus floating, beily up- 
ward, on the surface of the water. Very few, and these only 
northern species, are used as food, the flesh of the tropical 
forms being generally poisonous, and that often in a higher 
degree than any other fishes whatever. 
The Triodontide.— The most generalized family is that of 
the Triodontide. These fishes approach the Balistide in several 
