The Scleroderms.—The Sclerodermi include three recent and one extinct families. Of the recent forms, Triacanthidæ is the most primitive, having the ventral fins each represented by a stout spine and the skin covered with small, rough scales. The dorsal has from four to six stiff spines.
Triacanthodes anomalus is found in Japan, Hollardia hollardi in Cuba. Triacanthus brevirostris, with the first spine very large, is the common hornfish of the East Indies ranging northward to Japan.
Fig. 345.—The Trigger-fish, Balistes carolinensis Gmelin. New York.
The Trigger-fishes: Balistidæ.—The Balistidæ, or trigger-fishes, have the body covered with large rough scales regularly arranged. The first dorsal fin is composed of a short stout rough spine, with a smaller one behind it and usually a third so placed that by touching it the first spine may be set or released. This peculiarity gives the name of trigger-fish as well as the older name of Balistes, or cross-bow shooter. There are no ventral fins, the long pelvis ending in a single blunt spine. The numerous species of trigger-fishes are large coarse fishes of the tropical seas occasionally ranging northward. The center of distribution is in the East Indies, where many of the species are most fantastically marked. Balistes carolinensis, the leather-jacket, or cucuyo, is found in the Mediterranean as also on the American coast. Balistes vetula, the oldwife, oldwench, or cochino, marked with blue, is common in the West Indies, as are several other species, as Canthidermis sufflamen, the sobaco, and the jet-black Melichthys piceus, the black oldwife, or galafata. Several species occur on the Pacific Coast of Mexico, the Pez Puerco, Balistes verres, being commonest. Still others are abundant about the Hawaiian Islands and Japan. The genus Balistapus, having spinous plates on the tail, contains the largest number of species, these being at the same time the smallest in size and the most oddly colored. Balistapus aculeatus and Balistapus undulatus are common through Polynesia to Japan. Most of the tropical species of Balistidæ are more or less poisonous, causing ciguatera, the offensive alkaloids becoming weaker in the northern species. Melichthys radula abounds in Polynesia. In this species great changes take place at death, the colors changing from blue and mottled golden green to jet black. Other abundant Polynesian species are Xanthichthys lineopunctatus, Balistes vidua, Balistes bursa, and Balistes flavomarginatus.
Fig. 346.—File-fish, Osbeckia lævis (scripta). Wood's Hole, Mass.
Fig. 347.—The Needle-bearing File-fish, Amanses scopas of Samoa.
The File-fishes: Monacanthidæ.—Closely related to the Balistidæ are the Monacanthidæ, known as filefishes, or foolfishes. In these the body is very lean and meager, the scales being reduced to shagreen-like prickles. The ventral fins are replaced by a single movable or immovable spine, which is often absent, and the first dorsal fin is reduced to a single spine with sometimes a rudiment behind it. The species are in general smaller than the Balistidæ and usually but not always dull in color. They have no economic value and are rarely used as food, the dry flesh being bitter and offensive. The species are numerous in tropical and temperate seas, although none are found in Europe. On our Atlantic coast, Stephanolepis hispidus and Ceratacanthus schœpfi are common species. In the West Indies are numerous others, Osbeckia lævis and Alutera güntheriana, largest in size, among the commonest. Both of these are large fishes without ventral spine. Monacanthus chinensis, with a great, drooping dewlap of skin behind the ventral spine, is found on the coast of China. Of the numerous Japanese species, the most abundant and largest is Pseudomonacanthus modestus, with deep-blue fins and the ventral spine immovable. Another is Stephanolepis cirrhifer, known as Kawamuki, or skin-peeler. Alutera monoceros, and Osbeckia scripta, the unicorn fish, abound in the East Indies, with numerous others of less size and note. In the male of the Polynesian Amanses scopas (Fig. 347) the tail is armed with a brush of extraordinarily long needle-like spines.