JAPANESE FISHES. 
603 
GADOMUS Regan. 
Gadomus Regan, Ann. Mag. Nat. Hist., 1903, p. 459 (longifilis). 
Head large, fleshy, without prominent ridges, spiny armature or external depressions; nape elevated, 
hump-like. Snout broad, obtuse, not produced; mouth terminal, very large, with small villiform 
teeth or none; suborbital ridge very low, not joined to the angle of the preoperculum. Maxillary 
entirely received within a groove under the prefrontal and suborbital bones, its tips narrowed and 
blade-like; premaxillaries protractile downward, separated anteriorly, rib-shaped, compressed verti- 
cally, very broad and without true teeth; provided posteriorly with a short flange, which is received 
under the maxillary; mandible received within intermaxillary bones, without true teeth, but with 
minute asperities, similar to those in the upper jaw; vomer and palatines toothless. Barbel well 
developed. No pseudobranchiae. Gillrakers numerous, moderate, lanceolate, with minute denticu- 
lations along their inner edge. Branchiostegal membrane free from isthmus, deeply cleft. Branch - 
iostegals 7, very stiff. Gill-opening very wide; gills 4, a slit behind last gill; anterior gill-arch free. 
Operculum with a blunt, spine-like prominence at its angle. A round foramen, as usual in fishes, entirely 
within the hypercoracoid. Yentrals below pectorals, many-rayed, anterior rays produced; dorsal con- 
sisting for the most part of branched rays, higher than anal, the first dorsal low, without differentiated 
spine. Scales cycloid, unarmed; lateral line strongly arched over pectoral. Deep seas. 
This genus, with Bathygadus, differs from Macromus and its allies in the structure of both the first 
and last gill arches. It is, perhaps, the most primitive of the family, and as such is nearest allied to 
the Gcididx. 
According to Regan, this genus differs from all other Macrouridx in the presence of a foramen 
within the hypercoracoid bone as in ordinary fishes, not between the coracoids as in gadoid fishes, 
and from Bathygadus in having a slit behind the last gill, as usual in Macrouridx. The mental barbel 
is well developed. In the related genus Melanobranchus Regan, the foramen is between the coracoids; 
the hypercoracoid being imperforate, there is no barbel, and a slit is present behind the last gill. 
( Gadus , cod; oopos, shoulder.) 
85. Gadomus colletti Jordan & Gilbert, new species. 
Type 332 mm. long; from station 3721, Suruga Bay, 207 to 250 fathoms. No. 50930, U. S. Nat. Mus. 
First dorsal ii, 10; ventrals, 9; pectorals, 21. Gillrakers 4 or 5+19. Branch iostegals, 7. Head 
5.4 in total length; depth 7.33. 
This species is related to Gadomus multijilis, longifilis, and melanopterus, the head narrow and com- 
paratively firm, mucous canals not excessively developed, mental barbel very long. Interorbital width 
much less than orbital diameter or length of snout and contained 6 times in length of head. Horizontal 
diameter of eye a trifle less. Length of snout 3.57 in head; snout not blunt at tip. Vertical width of 
suborbital beneath middle of orbit 5.6 in head. Occipital crest long, the distance from its posterior 
end to dorsal contained 3.8 times in its distance from tip to snout. Mouth moderately oblique the 
mandible everywhere included, maxillary not reaching vertical from hinder edge of orbit, its length 
half that of head. Teeth excessively minute, crowded, forming a wide band in premaxillaries, a much 
narrower band in mandibles. The premaxillary band increases in width laterally to end of second 
third of its length, its width there equaling one-third the orbital diameter. Individual teeth are 
scarcely to be made out, and constitute, a fine shagreen-like surface. Barbel very long, two-thirds the 
length of head. Preopercle rather narrowly rounded, width at angle slightly increased, about two- 
fifths orbital diameter. Opercle firm, without evident ridges or spines. 
The gill-membranes form a rather wide free fold across the isthmus, to which they are not joined. 
No trace of pseudobranch ise can be detected. Gills 4 in number, the large slit behind the fourth arch 
equaling orbital diameter. Gillrakers very slender and comparatively short, the longest one-third the 
orbital diameter. A very deep pit marks the usual pseudobranchial area, more developed than in 
related species. Hypercoracoid with a well-marked foramen, as in blennioid fishes. 
Second dorsal spine, second pectoral and outer ventral ray enlarged and greatly elongated; dorsal 
ray 3.66 times in total length; pectoral ray 3 times; ventral ray 5.5 times. Base of pectoral fin in 
advance of insertions of first dorsal and ventral which are vertically opposite; first dorsal spine repre- 
sented by a small nodule, concealed at base of second; succeeding rays forked in their distal third, the 
longest articulated ray three-fifths length of head; no interval between dorsals; longest ray of the 
