One of the most remarkable among the deep-sea Eels is the Snub-nosed Eel (Simenchelys parasiticus), which has been found in great numbers off Newfoundland and the Azores, at depths of 200 to 900 fathoms. The maxillary and mandibular bones are very short and massive, provided with large obtuse teeth; the head is short and bulldog-like in aspect, the mouth small and bordered by a thick circular lip. Some specimens have been observed to burrow in the muscles of living Halibut and other large Fishes, after the manner of Myxine.
Fam. 2. Nemichthyidae.—Distinguished from the preceding by the position of the vent, which is close to, or at no great distance from, the gill-openings. The rays of the vertical fins are connected by thin membrane instead of being imbedded in thick skin, as in most Eels; in some of the genera the jaws are excessively prolonged, needle-like, sometimes recurved. Deep-sea Eels of small size, represented in the Atlantic, Pacific, and Indian Oceans by about 10 species, referred to 6 genera: Dysomma, Dysommatopsis, Nemichthys, Spinivomer, Serrivomer, Gavialiceps.
Fam. 3. Synaphobranchidae.—Maxillaries narrowly separated on the median line, their extremity strongly attached by ligament to the mandible; pterygo-palatine arch absent. Gill-openings externally confluent into a single ventral slit. Deep-sea Fishes, resembling the true Eels in the general form and in the presence of linear scales placed at right angles, but differing in the absence of the pterygo-palatine arch, as in the Saccopharyngidae. Eight species of Synaphobranchus are known, from the Atlantic, Pacific, and Indian Oceans, at depths of 200 to 2000 fathoms.
Fam. 4. Saccopharyngidae.—Maxillaries narrowly separated on the median line, extremely elongate; mouth enormous; pterygo-palatine arch absent; hyomandibular arch slender and movably articulated to the cranium, the two bones (hyomandibular and quadrate) of which it is composed being capable of being swung in all directions; branchial arches far behind the skull; no branchiostegal rays or pharyngeal bones.
Extraordinary-looking deep-sea Fishes allied to the Eels, of which they appear to be a further degraded type, the muscles being feebly developed and the skeleton imperfectly calcified. The mouth, furnished with rather long but feeble, or even minute teeth, and the pharynx and stomach are capable of great distension, these Fish being able to get outside a prey very much larger than themselves; the eyes are situated far forward on the head; the tail is extremely slender and elongate. Four genera are known, each with a single species, from the Atlantic: Saccopharynx, Eurypharynx, Macropharynx, and Gastrostomus. The depths at which they have been obtained vary between 389 and 1467 fathoms, but three out of the four known specimens of Saccopharynx were brought to the surface by having swallowed a Fish too large for the capacity of the stomach. The length of the largest specimen is about 6 feet, of which the tail constitutes nearly three-fourths.
Fig. 364.—Saccopharynx ampullaceus, ⅓ nat. size. (After Günther.)
Fig. 365.—Skull of Thyrsoidea meleagris, side view, ar, Articular; d, dentary; eot, epiotic; eth, ethmoid; f, frontal; hm, hyomandibular; iop, interoperculum; n, nasal; op, operculum; os, orbitosphenoid; p, parietal; pop, praeoperculum; por, praeorbital; ppt, pterygo-palatine; ps, parasphenoid; ptf, post-frontal; q, quadrate; so, supraoccipital; sop, suboperculum; sor, suborbitals; sq, squamosal; v, vomer.
Fam. 5. Muraenidae.—Maxillaries absent, replaced by the palato-pterygoid, the mouth bordered by the latter and the ethmo-vomer; palato-pterygoid bone separated from hyomandibular arch; branchial openings into the pharynx narrow slits; no tongue.