382 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
forward almost to the front of the premaxillaries. No trace of a 
_mandibular barbel can be detected on any of the specimens. * Small 
inclosed pseudobranchiae are present on all specimens, and are 
located, as in the other species, beside a deep conic pit. The gill- 
rakers are always denticulate along their inner edges, but are 
variable in width and in length; the longest one, near the angle of 
the first gill arch, is contained 1.8 (1.2 to 1.6) times in the orbit; 
the number of gill-rakers is 6+20 on the left, and 6+22 on the 
right side of the type (6 or 5+19 to 21 in paratypes). Four full 
gills are present, the last of which is short, and followed by a sht 
about half as wide as the interorbital space. The branchial aperture 
is continued forward almost to the vertical from the anterior orbital 
margin. Seven branchiostegals. As in B. antrodes, the scapular 
Fig. 1.—BATHYGADUS SPONGICEPS. ‘TYVE. 
foramen, though encroaching eutirely upon the substance of the 
hypercoracoid, is in contact with the suture separating that bone 
from. the hypocoracoid. 
The scales which separate the lateral line series from the front of 
the second dorsal fin are arranged in six horizontal series. Several 
much enlarged scales or scale-like bones are present in the sensory 
canal above the gill openings. The shoulder girdle is scaleless be- 
neath the opercles. 
The first dorsal spine is soft and concealed, but is slender, sharp, 
and about one-fifth as long as the orbit; the smooth second dorsal 
spine is contained 1.6 times in the head; the second pectoral and the 
outermost ventral rays are likewise scarcely strengthened or pro- 
duced. In this respect B. spongiceps differs notably from B. an- 
trodes, in which the three rays are strengthened and greatly length- 
ened. The base of the ventral fin is anterior to the base of the 
pectoral, which is nearly in line with the origin of the first dorsal. 
The distance from the center of the anus to the base of the outer 
ventral ray is contained 1.6 (to 1.8) times in the head. 
