In Thalassophryne, from the coasts of Central America, the opercular spine and the two dorsal spines are perforated, and convey poison from subcutaneous sacs situated at their base.[[752]] In the American genus Porichthys the head and body bear series of greatly developed mucous pores, some of which simulate the photophores of Scopelus, but are not luminous.[[753]]
Fig. 429.—Porichthys porosissimus. (After Goode and Bean.) ½ nat. size.
Fam. 11. Pholididae.—Suborbitals not forming a subocular shelf; mouth scarcely protractile, with thick lips. Praecaudal vertebrae similar to the caudals, without transverse processes, with hæmal arches; ribs sessile. Gill-membranes free from the isthmus; 4 or 5 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae present. Scapular arch as in Blenniidae. Ventral fins jugular and rudimentary, or absent. Body elongate, compressed, with very small scales. Dorsal and anal fins elongate, the former constituted entirely of non-articulated rays or spines. Caudal fin distinct, with expanded hypuraL.
Small shore fishes of the Northern Seas, differing from the Blenniidae in the structure of the praecaudal vertebrae, in spite of the external resemblance which the two known genera, Pholis (Centronotus) and Apodichthys, bears to Anoplarchus and Xiphistes. Species about 10.
A well-known British fish of this family is the little Gunnel or Butter-Fish (Pholis gunnellus), remarkable for the manner in which the female protects her offspring, coiling herself round the eggs, which she rolls up into a ball about the size of a Brazil nut, in holes of the boring Mollusc (Pholas). The male sometimes assists the female.
Fam. 12. Zoarcidae.—Suborbitals not forming a subocular shelf; mouth feebly protractile. Praecaudal vertebrae with strong transverse processes bearing ribs and epipleurals. Gill-membranes usually more or less broadly united to isthmus; 5 to 8 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae present or absent. Scapular arch as in Blenniidae. Ventral fins jugular or absent; if present, with 1 to 4 rays. Body more or less elongate, naked or with very small scales. Dorsal and anal fins elongate, all the rays articulated, or a few of the posterior dorsals spinous. Usually no distinct caudal fin.
Fig. 430.—Typhlonus nasus × ½. (After Güther.)
These fishes have usually been placed, in part at least, near the Gadids, but they have more in common with the Blenniids, as pointed out by Jordan and Evermann, and may be regarded as degraded forms descended from the latter.[[754]] The family is widely distributed in all seas, many of the forms being specially adapted to live at great depths. The species known number about 130. Principal genera: Scytalina, Zoarces, Lycodes, Gymnelis, Lycocara, Melanostigma, Derepodichthys, Bathyonus, Porogadus, Bythitis, Neobythitis, Cataetyx, Selachophidium, Acanthonus, Typhlonus, Aphyonus, Tauredophidium, Rhodichthys, Brosmophycis, Brotula, Lucifuga, Lamprogrammus, Diplacanthopoma, Hephthocara.