436 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 
series). There are five or six rows of scales between the origin of 
the second dorsal fin and the lateral line series. 
The scales on the head are in general quite similar to those of the 
body, but the spinules on them are stronger and more nearly erect. 
The spinules along the weak ridges of the head are often arranged 
in strongly divergent series, and are comparatively little strength- 
ened. The dorsoterminal rostral plate is poorly developed, being 
scarcely produced in the larger specimens. The scales along the in- 
fraorbital ridge are flat; only along the ventral margins of these 
scales are the spinules strengthened; these ridge scales are in a single 
series before the middle of the eye, but are in two series posteriorly. 
The median rostral ridge is covered by quadrate scales in a series 
continued backward almost to the median occipital scute; this median 
series is flanked on each side by a single series of scales. The occipi- 
tal scute is preceded by a partly scaled area, and is immediately fol- 
lowed by a similarly strengthened scale. The large and irregular 
scales between the occipital and the postorbital ridges cover the sen- 
sory canal already described; this area is well defined, and is con- 
tinued backward to below the origin of the first dorsal fin, being 
confined to the region below the scaleless groove continuous with the 
lateral line (the scales in the posterior portion of the area are of 
decreased size). Only a few weakly spinous or smooth scales are 
present on the lower part of the nasal fossa, and between the orbit 
and the infraorbital ridge; the anterolateral region of the snout is 
largely naked; the ind eneide of the head is wholly scaleless, includ- 
ing the bremeinaeeoal membranes, but excluding a_ well-defined 
and highly diagnostic crescent- ered area just below and within the 
anterolateral margins of the snout. 
The base of the first dorsal fin is contained 1.4 (to 1.05) times 
in the interval between the two dorsals, and 2.0 (to 1.6) times in 
the postorbital length of the head. The anterior rays of the second 
dorsal fin are very short. The origin of the anal fin is behind that 
of the second dorsal, and also (with few exceptions) behind the 
end of the pectoral. The ventral fin never reaches the anus excepi 
in very young individuals. Length of the fin rays in the head 
(in specimens exclusive of the type)—second dorsal spine, 1.95 to 
2.5; pectoral fin, 2.2 to 2.9; outer ventral ray, 2.6 to 3.3; inner 
ventral rays, 3.3 to 4.2. 
Coloration in alcohol.—The body, especially in the young, is 
marked by dark mottling on the trunk and by numerous dark 
vertical bars on the tail. The ventral portion of the branchiostegal 
membrane is jet black; the gular membrane is crossed by numerous 
fine black lines on minute ridges, between which the silvery ground 
color is prominent. This type of coloration is not to be confused 
with the true striations of Hymenocephalus, for in that genus 
