404 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
without light margins. The first dorsal fin is ight throughout; the 
second dorsal has a narrow light streak near its base, but the main 
part of the fin is dusky, shading into black anteriorly; the anal is 
dusky throughout. The dusky pectoral fin becomes lighter toward 
the tip of the filamentous ray and blackish near the base of the fin. 
The blackish ventral fin becomes lighter toward the inner margin of 
its base. 
This species, together with G. multifilis, is readily distinguishable 
from denticulatus, colletti, and magnifilis, differmg from all in the 
wider interorbital space and the wholly dark branchial cavity, from 
denticulatus and colletti also in the coarser dentition, and from 
magnifilis also in the shorter fin filaments. The number of pyloric 
caeca seems also to-be characteristic of the species; there are 24 to 29 
in magnifilis, 35 to 52 in introniger, 61 to 75 in denticulatus, and 95 
in colletti. 
From G. multifilis, G. introniger differs in a number of diagnostic 
characters: the gill-rakers are shorter, more widely spaced and 
bluntly, instead of sharply, tipped, and they are fewer in number, 
there being 20 to 24 instead of 26 below the angle of the outer arch; 
the head is much firmer, the sensory channels being less developed ; 
the teeth are considerably finer, and in wider bands, the premaxillary 
band being contained 2.2 to 3.0 in the suborbital width, rather than 3.3 
to 3.8 times; the body is a little more robust, the depth in G. multi- 
filis not equaling the length of the head to the angle of the preoper- 
cular ridge; the distance between the anus and the base of the ventral 
is decidedly longer, being two-thirds instead of half as long as the 
head; there are 7 instead of 6 scales above the lateral line; the 
fin filaments are shorter, the dorsal spine and the outer ventral ray 
being shorter, instead of longer, than twice the length of the head. 
G. introniger differs in similar details from G. melanopterus of Ha- 
wail, and from G@. longifilis in the wider interorbital, wider bands of 
teeth, and especially in the fewer gill-rakers (see measurements and 
counts of G. longifilis in the table of measurements and counts of the 
next species, G. multifilis). The number of pyloric caeca proves 
valuable in distinguishing these species also; 35 to 52 were counted in 
G. introniger, 12 to 16 in G. multifilis, 15 in G. melanopterus, and 
but 8 in G. longifilis. 
This species lives in water probably deeper, on the average, than 
that inhabited by G. denticulatus. Its general appearance and struc- 
ture is in harmony with such a difference in distribution. G. introni- 
ger inhabits depths as great as those from which G. magnifilis was 
dredged, but in much colder water. 
