148 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
nictitating membrane; spiracles well developed behind the eye; gill- 
openings moderate, in advance of the pectoral; jaws armed with numer- 
ous rows of small, tricuspid teeth; first dorsal fin, opposite the space 
between pectorals and ventrals, long and low, gradually increasing in 
height posteriorly ; second dorsal behind ventrals, oppesite and similar 
to anal; ventrals and pectorals well developed; no pit at the root of 
caudal fin, the basal lobe of which is very low and long ; skin with mi- 
nute asperities. 
The genus Pseudotriacis was provisionally referred to the family Seyl- 
liide, in which it properly belongs. 
PSEUDOTRIACIS MICRODON Capello. 
The greatest height of the body is at the origin of the first dorsal ; 
it is contained 83 times in the total length. The height at the origin of 
ventrals is contained 94 times in total length. The height of head at 
the first gill-opening is a little greater than that of body at the ventral 
origin, while the height of the head at the angle of the mouth is a little 
less than one-eleventh of the total length. The least height of the tail 
equals the height of the anal, and is contained 25 times in total 
length. 
The head is somewhat depressed in front, with moderately sharp 
snout, which is nearly twice as long as the distance of its tip from the 
mouth. The distance from snout to last gill-opening is contained 5 
times in total length. The distance from snout to first gill-opening, 
measured horizontally, equals twice the height of body at origin of sec- 
ond dorsal. The distance between the first and last gill-openings equals 
nearly twice the length of the eye. The height of the first gill-opening 
is about equal to the distance between the angle of the mouth and the 
spiracle. The height of the head at angle of mouth is contained 11 
times and at the first gill-opening 9 times in total length. The length 
of the snout equals one-half the body height at origin of first dorsal. 
The distance of mouth from snout, measured on the axis of the fish, 
equals one-third width of mouth. The distance from snout to angle of 
mouth, obliquely taken, equals one-fourth the distance from snout to 
last gill-opening. The distance between eye and spiracle equals that 
from mouth to nostril. The distance from angle of mouth to spiracle is 
about equal to height of first gill-opening. The spiracle is moderately 
large, the length of its opening being contained twice in the height of 
fourth gill-opening. The oblong eye is placed near the dorsal profile ; 
the length of the orbit is about one-half the greatest height of second 
dorsal; the length of the eye equals about one-fourth width of mouth. 
The length of upper jaw is slightly more than that of lower, and nearly 
equals the distance between the spiracles. The distance from the mouth 
to the nostril is about one-fourth least height of tail; the distance be 
tween nostrils equals 4 times the distance from eye to spiracle. The 
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