450 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
slightly downward, and bears a series of strengthened scales armed 
with a single keel, along which eight or fewer rather strong spinules 
project outward and backward. The occipital ridges are subparallel 
anteriorly, but diverge posteriorly; the least distance between them 
is contained 1.8 (1.5 to 1.9) times in the interorbital width; the scales 
on the occipital ridges bear from one to three (usually one) spinous 
carinae, but are rougher in small. specimens. The median occipital 
scute bears a single keel in the type and in the larger paratypes, but 
three ridges in the small paratypes; a similar scute is situated at the 
origin of the lateral line. A row of enlarged scales, the largest of 
all, is located midway between the occipital and postorbital ridges; 
these large scales have seven or fewer divergent carinae; the remain- 
ing scales between those ridges are small or minute. The space be- 
tween the front half of the occipital ridges is covered by five series 
of scales; the scales of the median series are the largest, and bear 3 
(2 to 4) divergent carinae; those of the outermost series on each side 
are smaller, and bear 2 or 3 carinae; those of the intervening series 
are minute. The two series of sparsely spinulate scales bounding the 
median rostral series on each side become narrow anteriorly, so that 
their lateral margins converge forward and meet the median series 
just behind the terminal plate. A conspicuous scaleless groove sepa- 
rates these series from the single series bounding the supranarial 
ridge. An area of scales like those of the body is located behind the 
upper half of the orbit. 
The first dorsal spine is sharp, but very short; the second spine is 
produced into a filament, and is almost as long as the head in the 
type. The base of the first dorsal is slightly longer than the length 
of the interdorsal space in the type, and is contained from 0.9 to 1.2 
times in that distance in the paratypes. The anterior rays of the sec- 
ond dorsal fin are comparatively well developed, being 0.3 as long as 
the orbit. The origin of the anal fin is directly below that of the 
second dorsal. 
The length of the fin rays forms a notable sexually dimorphic 
character. They are decidedly longer in the males than in the 
females, as is indicated in the following table: 
Table of measurements of length of fins in each sex.* 
a Females. 
Males 
(Paratypes). 
Paratypes. Type. 
Second dorsal spine.......-.--- Seesiz = te Set eae ey Brees Se Se ee 0.8 to 0.9....-. 
1.17 to 1.55. 1.02 
PeChOral Tin. 2... secmise cess Sale =e Seen cet ee teal eect see tote 1.15 to 1.50....| 1.60 to 2.15. 1.80 
Outer ventral rayiecs sete se ten sees Sen eet, a ete eee enee Lditontss..0 see 1.7 to 3.0-. 1.95 
Second ventral ray... -.-....-..-- aoe Soenc eee waaeneT CORR See Ca s24 tO 217s 42:9 TOs aoe 3.27 
1 Expressed in the number of times the length of each ray or fin is contained in the head. 
