Tenth Family—Batrachidæ.
Head broad and thick; body elongate, compressed behind; skin naked or with small scales. No bony stay for the præoperculum. Teeth conical, small or of moderate size. The spinous dorsal consists of two or three spines only; the soft and the anal long. Ventrals jugular, with two soft rays; pectorals not pediculated. Gill-opening a more or less vertical slit before the pectoral, rather narrow.
Carnivorous fishes, of small size, living on the bottom of the sea near the coast in the tropical zone, some species advancing into the warmer parts of the temperate zones.
Batrachus.—The spinous dorsal is formed by three stout spines. Gill-covers armed with spines. Circumference of the mouth and other parts of the head frequently provided with small skinny tentacles.
Some of the fishes of this genus possess a subcutaneous spacious cavity behind the base of the pectoral fin, the inside of which is coated with a reticulated mucous membrane. It opens by a foramen in the upper part of the axil.—This apparatus is the same which is found in many Siluroid fishes, and which has been noticed above, p. 192. There cannot be any doubt that it is a secretory organ, but whether the secretion has any poisonous properties, as in the Siluroids, or as in Thalassophryne, has not been determined. No instance of poisonous wounds having been inflicted by these fishes is on record. Twelve species are known, the distribution of which coincides with that of the family; one very fine species, B. didactylus, occurs in the Mediterranean.
Thalassophryne.—The spinous dorsal is formed by two spines only, each of which is hollow, like the opercular spine, and conveys the contents of a poison-bag situated at its base. Canine teeth none.
Fig. 208.—Thalassophryne reticulata.
Two species are known from the Atlantic and Pacific coasts of Central America. The poison-apparatus is more perfectly developed than any other known at present in the class of fishes; it has been described above, p. 192. The species figured, Th. reticulata, is not uncommon at Panama, and attains to a length of fifteen inches.
Porichthys.—Two small dorsal spines; a canine tooth on each side of the vomer.