Fam. 36. Scaridae.—Closely allied to the preceding, with which they have usually been united, but differing in the more or less coalescent teeth, forming often a parrot-like beak, the lower pharyngeals united into a concave or spoon-shaped bone with flat, tessellated teeth; and in the development of transverse processes from the first vertebra. Vertebrae 24 or 25.
Fig. 413.—Upper and lower pharyngeal bones of Scarus strongylocephalus. (After Jordan and Evermann.)
Curious, mostly brilliantly-coloured fishes of the tropical seas and the Mediterranean, especially abundant about coral-reefs. "Parrot-Wrasses" feed mostly on vegetable matter, corals, and on hard-shelled Mollusca, for crushing which their dentition is well adapted. The largest reach a length of 4 feet. Some are much valued as food, whilst others are reputed poisonous. About 110 species are known, referable to 8 genera: Cryptotomus (Calliodon), Calotomus, Sparisoma, Scarus, Pseudoscarus, Odax, Coridodax, Siphonognathus. The latter is very aberrant in shape, the head and body resembling those of a Pipe-Fish.
Scarus is reported from the Eocene and Miocene of Europe.
Division II.—SCOMBRIFORMES.
No bony stay for the praeopercle. Spinous dorsal, if distinct, formed of short or feeble, slender spines. Epipleurals usually attached to the centra when ribs are sessile, or to the parapophyses of the vertebrae, rarely to the ribs. Pectoral arch similar to that of the Perciformes, but pterygials sometimes more abbreviated. Ventral fins thoracic. Caudal fin, if well developed, with very numerous rays deeply forked at the base.
Fig. 414.—Caudal fin of Sarda orientalis. h.s, Hypural spine.
Although bound by natural ties, the series of families that cluster round the Mackerel offer so many modifications of structure that it is almost impossible to draw up a diagnosis differentiating every one of its members from the Perciformes, with which they are closely connected, and from which they hardly deserve to be separated. Even after removing many genera which have been united with them by my predecessors, and which will now be found scattered among various groups of the system, no good definition of the Scombriformes can be given. The Mackerel and Horse-Mackerel are taken as the pattern-forms around which more or less aberrant types are located, types yet not so aberrant as to be traced back to these familiar forms through a number of intermediate grades. As regards external features, it may be stated that the dorsal and anal spines, if present, are either weak and slender, or, if strong, short and detached; the caudal peduncle is constricted, and the caudal fin, if well developed, is usually deeply forked, and with the forked bases of the very numerous rays much longer than in most of the Perciformes, embracing at least a considerable portion of the expanded hypural bones, a character by which the Chaetodontidae, Acanthuridae, and several extinct types which have been placed with the Carangidae are at once excluded. All are carnivorous and marine, and many are pelagic and of very wide distribution. No praetertiary members of this division, as here defined, have yet been found.