FRIGATE-MACKEREL. 
109 
If we compare these measurements with the above- 
mentioned figures of Day or Brown-Goode, which 
represent young specimens, we shall find that the cor- 
responding proportions are, respectively, 29 — 30, GO- 
62, and 66 — 68. Hence we conclude that in the Fri- 
gate-Mackerel, as in the Mackerels, the length of the 
preabdominal region, as well as its height, increases 
with age, a state of things directly opposed to that 
we have observed above in the Tunnies, whose growth 
consists, to a great extent, in the elongation of the 
caudal region, and in which the dorsal and anal fins 
seem, in relation to the length of the body, to approach 
the tip of the snout as they grow older. 
In the Frigate-Mackerel the form of the head is 
especially marked by the short, but pointed, snout and 
the sharply curved (almost elliptic) hind margin of the 
preoperculum. The length of the head about 1 / i of 
that of the body. The eyes fairly small in proportion 
to the length of the head (between 19 and 17 %), but 
large in proportion to the length of the snout, of 
which they measure 75 %. Of the breadth of the in- 
terorbital space they measure 60 %. The gape com- 
paratively small. When the mouth is closed, a great 
portion, even of the back part, of the upper jaw-bone 
is covered by the preorbital bone and its dermal flap; 
but the lower posterior corner and a part of the hind 
margin of the jaw-bone falls into a cavity in the ex- 
ternal margin of the lower jaw. The margin of the 
gill-covers ciliated. The corslet well defined, with a 
depression, as usual, on each side for the pectoral fins 
and one common to the ventral fins. The uppermost 
of its points, which are directed backwards, extends 
to a point midway between the two dorsal fins, the 
middle ones, one on each side, follow the lateral line 
for some distance, and the lowest extends along the 
belly to a point somewhat behind the ventral fins. 
Of the sinuses, which are directed forwards, the upper 
extends to the end of the first dorsal fin or even as 
far as its 5th or 4th ray, and the lower to a perpen- 
dicular through the insertions of the pectoral and vent- 
ral fins. Behind the corslet the lateral line is undu- 
lating. The caudal carinai are weaker than in the true 
Tunnies. The pectoral fins are fairly short, being a 
little longer than the venfral and somewhat less than 
Vg of the length of the body. They do not extend 
quite so far back as the first dorsal. The first two 
rays in the first dorsal are the longest, the last two 
very short and the last of all generally so short that 
it scarcely projects above the margin of the fin-groove. 
The second dorsal and the anal fins are low and scaly. 
The internal organs essentially correspond, accord- 
ing to Cuvier, to those of the Tunnies. The long 
tubular gall-bladder is especially remarkable. There 
is no air-bladder. 
The colouring of the body, which on the whole 
resembles that of the Tunnina {Euthynnus allitteratus ) 
is particularly subject to variations in the distinctness 
of the spots and of the dark, irregular, wavy transverse 
streaks on the back, which sometimes seem to have 
vanished entirely. The pectoral fins silver-gray on the 
outside and black on the inside. The other fins gray, 
the anal shading into yellow. 
The Frigate-Mackerel is common in Japan, was 
seen in crowded shoals by Commerson off New Guinea 
and has long been known as a common fish in the 
Mediterranean. Like the Pelamis, it has latterly ap- 
peared in huge masses of the east coast of North Ame- 
rica, where it has, however, been regarded up to now 
as an unwelcome intruder, its flesh being less esteemed 
than that of the other members of the family as it 
rapidly turns black on exposure to the air. “Its oil 
does not seem to be very abundant, and it will hardly 
pay at present to capture it solely for the purpose of 
using its flesh in the manufacture of fertilizers,” says 
Brown-Goode. It is equally despised, according to 
Risso, in the Mediterranean. When salted, however, 
it is said to be eatable. According to Risso its weight 
seldom exceeds 3 kgrm. Its greatest length is appa- 
rently about 45 cm. The spawning-season is supposed 
to be in August, when the female deposits her eggs, 
which are whitish and enveloped in a reddish mucus. 
The Frigate-Mackerel has been met with once or 
twice off the English coast and on one, single occasion 
in Scandinavian waters, at the fishing-village of Arild 
(Scania), where Baron Gyllenstjerna obtained a spe- 
cimen 377 mm. in length, which was described by 
Nilsson and is now preserved in the Zoological Mu- 
seum of Lund University. 
