Fig. 226.—Pempheris nyctereutes Jordan & Evermann. Giran, Formosa.
Fig. 227.—The Louvar, Luvarus imperialis Rafinesque. Family Luvaridæ. (After Day.)
Very close to the Pempheridæ is the small family of Bathyclupeidæ. These are herring-like fishes, much compressed and with a duct to the air-bladder. There are but one or two dorsal spines. The ventrals are of one spine and five rays as in perch-like fishes, but placed behind the pectoral fins. This feature, due to the shortening of the belly, is regarded by Alcock, the discoverer, as a result of degeneration, and the family was placed by him among the herrings. The persistent air-duct excludes it from the Percesoces, the normally formed ventrals from the Berycoidei. If we trust the indications of the skeleton, we must place the family with Pempheris, near the scombroid fishes.
Luvaridæ.—Another singular family is the group of Louvars, Luvaridæ. Luvaris imperialis. The single known species is a large, plump, voracious fish, with the dorsal and anal rays all unbranched, and the scales scurf-life over the smooth skin. It is frequently taken in the Mediterranean, and was found on the island of Santa Catalina, California, by Mr. C. F. Holden.
The Square-tails: Tetragonuridæ.—The Tetragonuridæ are long-bodied fishes of a plump or almost squarish form, covered with hard, firm, very adherent scales. Tetragonurus cuvieri, the single species, called square-tail, or escolar de natura, is a curious fish, looking as if whittled out of wood, covered with a compact armor of bony scales, and swimming very slowly in deep water. It is known from the open Atlantic and Mediterranean and has been once taken at Wood's Hole in Massachusetts. According to Mr. C. T. Regan the relations of this eccentric fish are with the Stromateidæ and Bramidæ, the skeleton being essentially that of Stromateus, and Boulenger places both Tetragonurus and Stromateus among the Percesoces.
The Crested Bandfishes: Lophotidæ.—The family of Lophotidæ consists of a few species of deep-sea fishes, band-shaped, naked, with the dorsal of flexible spines beginning as a high crest on the elevated occiput. The first spine is very strong. The ventrals are thoracic with the normal number, I, 5, of fin-rays. Lophotes cepedianus, the crested bandfish, is occasionally taken in the Mediterranean in rather deep water. Lophotes capellei is rarely taken in the deep waters of Japan.
It is thought that the Lophotidæ may be related to the ribbon-fishes, Tæniosomi, but on the whole they seem nearer to the highly modified Scombroidei, the Pteraclidæ for example.
In a natural arrangement, we should turn from the Bramidæ to the Antigoniidæ and the Ilarchidæ, then passing over the series which leads through Chætodontidæ and Teuthidæ to the Plectognaths. It is, however, necessary to include here, alongside the mackerels, though not closely related to them, the parallel series of perch-like fishes, which at the end become also hopelessly entangled, through aberrant forms, with other series of which the origin and relations are imperfectly understood. As the relations of forms cannot be expressed in a linear series, many pages must intervene before we can take up the supposed line of development from the Scombroid fishes to those called Squamipinnes.