Eighth Family.—Trachinidæ.
Body elongate, low, naked or covered with scales. Teeth small, conical. No bony stay for the præoperculum. One or two dorsal fins, the spinous portion being always shorter and much less developed than the soft; the anal similarly developed as the soft dorsal; no finlets. Ventrals with one spine and five rays. Gill-opening more or less wide. Ten or more than ten abdominal, and more than fourteen caudal vertebræ.
Carnivorous coast-fishes of small size, found in every quarter of the globe, but scarcely represented in the Arctic zone (Trichodon); on the other hand, they are rather numerous towards the Antarctic circle. All are bad swimmers, generally moving along the bottom in small depths. Only one genus (Bathydraco) is known from the deep-sea.
A genus which shows the principal characters of this family (Callipteryx), has been found in the tertiary deposits of Monte Bolca; it is scaleless. A second genus, Trachinopsis, has been recently described by Sauvage from the Upper Tertiary of Lorca in Spain; and a third (Pseudoeleginus) from the Miocene of Licata.
This family may be subdivided into five groups:—
1. In the Uranoscopina the eyes are on the upper surface of the head, directed upwards; the lateral line is continuous.
Uranoscopus.—Head large, broad, thick, partly covered with bony plates; cleft of the mouth vertical. Scales very small. Two dorsal fins, the first with from three to five spines; ventrals jugular; pectoral rays branched. Villiform teeth in the jaws, on the vomer and palatine bones; no canines. Generally a long filament below and before the tongue. Gill-cover armed.
The position of the eyes on the upper surface of the head, which these fishes have in common with many others, is well expressed by the name Uranoscopus (Stare-gazer). Their eyes are very small, and can be raised or depressed at the will of the fish. They are inactive fishes, generally lying hidden at the bottom between stones, watching for their prey. The delicate filament attached to the bottom of their mouth, and playing in front of it in the current of water which passes through the mouth, serves to lure small animals within reach of the fish. Eleven species are known from the Indo-Pacific and Atlantic, and one (U. scaber) from the Mediterranean; they attain rarely a length of twelve inches.
Leptoscopus.—Form of the head as in Uranoscopus, but entirely covered with a thin skin. Scales small, cycloid. One continuous dorsal; ventrals jugular; pectoral rays branched. Villiform teeth in both jaws, on the vomer and palatine bones; canines none. No oral filament. Gill-cover unarmed.
