=The Gymnodontes.=—The group of _Gymnodontes_, having the teeth united in a turtle-like beak, carry still further the degeneration 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, belly upward, 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. [Illustration: FIG. 355.—Skeleton of the Cowfish, _Lactophrys tricornis_ (Linnæus). ] =The Triodontidæ.=—The most generalized family is that of the _Triodontidæ_. These fishes approach the _Balistidæ_ in several regards, having the body compressed and covered with rough scales. The teeth form a single plate in the lower jaw, but are divided on the median line above. The compressed, fan-like, ventral flap is greatly distensible. _Triodon bursarius_, of the East Indies and northward to Japan, is the sole species of the family. [Illustration: FIG. 356.—Silvery Puffer, _Lagocephalus lævigatus_ (Linnæus). Virginia. ] =The Globefishes: Tetraodontidæ.=—In the _Tetraodontidæ_ (globefishes, or puffers), each jaw is divided by a median suture. The dorsal and anal are short, and the ventrals are reduced in number, usually fifteen to twenty (7 + 13 to 7 + 9). The walls of the belly are capable of extraordinary distension, so that when inflated, the fish appears like a globe with a beak and a short tail attached. The principal genus _Spheroides_ contains a great variety of forms, forming a closely intergrading series. In some of these the body is smooth, in others more or less covered with prickles, usually three-rooted. In some the form is elongate, the color silvery, and the side of the belly with a conspicuous fold of skin. In these species, the caudal is lunate and the other fins falcate, and with numerous rays. But these forms (called _Lagocephalus_) pass by degrees into the short-bodied forms with small rounded fins, and no clear line has yet been drawn separating the group into genera. In these species each nostril has a double opening. _Lagocephalus lagocephalus_, large and silvery, is found in Europe. _Lagocephalus lævigatus_ replaces it on the Atlantic Coast of North America. In Japan are numerous forms of this type, the venomous _Lagocephalus sceleratus_ being one of the best known. Numerous other Japanese species, _Spheroides xanthopterus_, _rubripes_, _pardalis_, _ocellatus_, _vermiculatus_, _chrysops_, etc., mark the transition to typical _Spheroides_. _Spheroides maculatus_ is common on our Atlantic coast, the puffer, or swell-toad of the coastwise boys who tease it to cause it to swell. _Spheroides spengleri_ and _S. testudineus_ abound in the West Indies. _Spheroides politus_ on the west coast of Mexico. [Illustration: