_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_. [Illustration: FIG. 346.—File-fish, _Osbeckia lævis_ (_scripta_). Wood's Hole, Mass. ] [Illustration: 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. In _Stephanolepis spilosomus_ the caudal fin is of a brilliant scarlet color, contrasting with the usual dull colors of these fishes. In _Oxymonacanthus longirostris_ the body is blue with orange checker-like spots and the snout is produced in a long tube. About the islands of Polynesia, filefishes are relatively few, but some of them are very curious in form or color. [Illustration: FIG. 348.—Common File fish, _Stephanolepis hispidus_ (Linnæus). Virginia. ] =The Spinacanthidæ.=—In the extinct family _Spinacanthidæ_ the body is elongate, high in front and tapering behind. The first dorsal has six or seven spines, and there are rough spines in the pectoral. The teeth are bluntly conical. _Spinacanthus blennioides_ and _S. imperalis_ are found in the Eocene of Monte Bolca. These are probably the nearest to the original ancestor among known scleroderms.