Amphistiidæ.—The Amphistiidæ, now extinct, are deep-bodied, compressed fishes, with long, continuous dorsal and anal fins in which a few of the anterior rays are simple, slender spines scarcely differentiated from the soft rays. The form of body and the structure of the fins are essentially as in the flounders, from which they differ chiefly by the symmetry of the head, the eyes being normally placed. Amphistium paradoxum is described by Agassiz from the upper Eocene. It occurs in Italy and France. In its dorsal and anal fins there are about twenty-two rays, the first three or four undivided. The teeth are minute or absent and there is a high supraoccipital crest.
The John Dories: Zeidæ.—The singular family of Zeidæ, or John Dories, agrees with Chætodonts in the single character of the fusion of the post-temporal with the skull. The species, however, diverge widely in other regards, and their ventral fins are essentially those of the Berycoids. In all the species there are seven to nine soft rays in the ventral fins, as in the Berycoid fishes. Probably the character of the fused post-temporal has been independently derived. The anterior vertebræ in Zeus, as in Chætodon, are closely crowded together. In the Zeidæ the spinous dorsal is well developed, the body naked or with very thin scales, and provided with bony warts at least around the bases of dorsal and anal fins. The species are mostly of small size, silvery in color, living in moderate depths in warm seas. The best-known genus is Zeus, which is a group of shore-fishes of the waters of Asia and Europe. The common John Dory (called in Germany Härings-König, or king of the herrings), Zeus faber, abounds in shallow bays on the coasts of Europe. It reaches a length of nearly a foot, and is a striking feature of the markets of southern Europe. The dorsal spines are high, the mouth large, and on the sides is a black ring, said by some to be the mark of the thumb of St. Peter, who is reported to have taken a coin from the mouth of this species. A black spot on several other species is associated with the same legend.
Fig. 197.—The John Dory, Zeus faber. Linnæus. Devon, England.
On the coasts of Japan abounds the Matao, or target-fish (Zeus japonicus), very similar to the European species and like it in form and color. Zenopsis nebulosa and Zen itea also occur on the coasts of Japan. The remaining Zeidæ (Cyttus, Zenopsis, Zenion, etc.) are all rare species occasionally dredged especially in the Australian region. Zeus priscus is recorded from the Tertiary, and Cyttoides glaronensis from the upper Eocene of Glavus.
Grammicolepidæ.—The Grammicolepidæ, represented by a single species, Grammicolepis brachiusculus, rarely taken off the coast of Cuba, is related to the Zeidæ. It has rough, ridged, parchment-like scales deeper than long. The ventrals are thoracic, with the rays in increased number, as in Zeus and Beryx, with each of which it suggests affinity.
CHAPTER XV
BERYCOIDEI
The Berycoid Fishes.—We may place in a separate order a group of fishes, mostly spiny-rayed, which appeared earlier in geological time than any other of the spinous forms, and which in several ways represent the transition from the isospondylous fishes to those of the type of the mackerel and perch. In the berycoid fishes the ventral fins are always thoracic, the number of rays almost always greater than I, 5, and in all cases an orbitosphenoid bone is developed in connection with the septum between the orbits above. This bone is found in the Isospondyli and other primitive fishes, but according to the investigations of Mr. E. C. Starks it is wanting in all percoid and scombroid forms, as well as in the Haplomi and in all the higher fishes. This trait may therefore, among thoracic fishes, be held to define the section or suborder of Berycoidei.
