APODAL FISHES OF AMERICA AND EUROPE. 
649 
apparently 11 or 12 in number, long and much curved, continuing around the pos- 
terior and upper edges of the opercles ; mouth with wide lateral cleft, notextending 
far beyond eye; maxillaries very wide, not extending far forwards, the clasping 
processes applied to shaft of vomer well behind its head. Teeth all conical, slender, 
and sharp, mostly depressible, those in jaws in wide bands; maxillary with a deep 
lengthwise groove, running the entire length of the bone and dividing the band of 
teeth into two portions; lower jaw much shorter than upper. Posterior nostril a 
linear slit, midway between eye and tip of snout; the anterior is a short tube just 
behind the head of vomer; tongue small, with the tip free; lips undeveloped ; the 
lateral line conspicuous. 
ANALYSIS OF THE SPECIES OF XENOMYSTAX. 
a. [Snout very long and slender ; end of maxillary equidistant from tip of mandible 
and gill-opening ; front of orbit over the beginning of last third of gape ; long 
slit-like pores on margin of upper jaw, a conspicuous series on mandible and 
preopercle; teeth in jaws in wide bands, mostly depressible; maxillary teeth 
divided by a deep groove running entire length of jaw, those on inner side of 
groove long, close-set, rigid, in single series ; mandible with much narrower and 
shallower groove, on the inner edge of which is a single series of very small coni- 
cal teeth, directed inwards; tip of mandible enlarged to form a knob which fits 
into a toothless depression just behind head of vomer, the vomer extending well 
beyond the tip of lower jaw ; teeth on head of vomer and knob of mandible simi- 
lar, slightly larger than those of side of jaw ; anterior part of shaft of vomer 
with median series of strong conical teeth, accompanied by smaller lateral series 
and followed by a narrower band of very small conical teeth. Head equal to 
trunk and £ of tail ; gill-openings broadly lunate, vertical length of slit £ of 
snout, interspace £ length of slit ; pectorals narrow, £ snout. Color very dark 
brown; fins black; pores of lateral line white.] ( Gilbert ) Atrarius, 97. 
c 
97. XENOMYSTAX ATRARIUS. 
Xenomystax atrarius Gilbert, mss. (off coast of Ecuador). 
Habitat : Deep waters of the eastern Pacific. 
Etymology : Atrarius , blackish. 
A single specimen, 18f inches long, was taken by the Albatross off the 
west coast of Ecuador at about lat. 1° S., long. 81° W., 401 fathoms. 
Family V.— NETTASTOMID^. 
This family, as understood by us, contains a few species of deep-sea 
eels closely allied to the Murcenesocidce in technical characters, but more 
resembling the Nemichthyidce in appearance, form of the head, and in 
dentition. The family, which is a provisional one, may be thus defined : 
Enchelycephalous eels without pectoral fins, with the tongue not 
free, the posterior nostrils remote from the lip, the gill- openings small, 
separate, and subinferior, the vent remote from the head, the tail end- 
ing in a slender tip or filament, the dorsal and anal fins moderately 
developed, and the jaws produced, slender, and straight, the upper the 
longer, and both, as also the vomer, armed with bands of sharp, close- 
set, recurved, subequal teeth. 
Three genera are known, deep-sea fishes with fragile bodies and the 
thin skin charged with black pigment. 
