SUN-FISH. This name is chiefly and properly applied to a marine fish {Orthagoriscus) which by its large size, grotesque appearance, and numerous peculiarities of organization has attracted the attention equally of fishermen as of naturalists. Only two species are known,—the rough or short sun-fish (O . mola), which is found in all seas of the temperate and tropical zones; and the much smaller and scarcer smooth or oblong sun-fish (O . truncatus), of which only a small number of specimens have been obtained from the Atlantic and Indian Oceans. That this genus belongs to the order Plectognathi and is allied more especially to the globe-fishes (Diodon and Tetrodon) has been indicated in the article Ichthyology (vol. ix. pp. 663, 694), where also the principal anatomical peculiarities have been noticed, and where illustrations of the young have been given (see figs. 64, 65).

Sun-fishes have the appearance of tailless fish. This is due to the extreme shortening of the tail, which is supported by only a few short vertebrae and reduced to a broad fringe of the trunk. Directly in front of it rise dorsal and anal fins, high and broad, similar to each other in size and triangular in form. The head is completely merged in the trunk, the boundary between them being indicated only by a very small and narrow gill-opening and a comparatively small pectoral fin. This fin can be of but little use in locomotion, and the horizontal and vertical movements of the fish, as well as the maintenance of its body in a vertical position, are evidently executed by the powerful dorsal and anal fins. The small mouth, situated in front of the head, is armed with an undivided dental plate above and below, similar to but weaker than the teeth of the globe-fish (Diodon)....