BOREAL PEARL-SIDE. 
935 
All the tins are light and transparent, with only the 
anterior margin or, in the caudal tin, the two outer 
margins, of the same colour as the back, or dark. 
Of the internal organs we shall merely remark, 
after Day, that the stomach is ciecal, the duodenum 
furnished with 8 rather large pyloric appendages, and 
the whole intestinal canal forms only two convolutions. 
The testes and ovaries are paired and long. 
The Pearl-side is a gregarious fish, and though it 
is most often met with in solitary specimens among 
small Herrings (Sprats and Herring-fry), it also appears 
in shoals of its own, instances of which have been ob- 
served on the coasts both of Finmark and England. 
Like Argyropelecus Olfersii, it is a pelagic and noc- 
turnal fish of extensive geographical distribution. It 
has been found on both sides of the North Atlantic, 
and differs but slightly, if indeed it be specifically 
distinct, from Maurolicus amethystino-punctatus, a Me- 
diterranean species with which Gunther has combined 
Maurolicus australis, a New Zealand form described 
by Hector. 
Within the limits of the Scandinavian fauna the 
Pearl-side was first discovered by Strom off Sondmor, 
and on the Swedish coast it was first taken by Nilsson, 
near Gothenburg, in a seine drawn for small Herrings. 
It has since been found at many points, both in Bo- 
huslan and Norway, cast ashore by the waves, or in the 
stomach of God and Herring". South of Bohuslan it is 
unknown on the Swedish coast, and only one find has 
been recorded on the west coast of Denmark, consisting 
of a specimen lying on the shore at Hjorring in the 
north of Jutland. On the Norwegian coast it is much 
commoner, north to Hammerfest, and ascends the fjords. 
In the Eyng, one of the Finmark fjords, east of Tromso, 
there appeared in 1866, according to Collett, a whole 
shoal of Pearl-sides. They could be scooped up in 
bucketfuls from the surface, and at least 50 specimens 
were preserved. Similar shoals have been seen on the 
coasts of Great Britain and Ireland, in the North Sea, 
the Channel, and the Irish Sea. According to Edward * * 6 
the Pearl-side is a regular winter visitor off Banff, 
never failing to appear in the month of January; and 
from January to March Mr. Sim gathered in two years 
nearly 200 specimens on the shore near Aberdeen. It 
would thus seem to be most common to the north; on 
the English coast south of Yorkshire only solitary spe- 
cimens have been found, and on the west coast of 
France, as well as in Holland, the species is unknown. 
On the east coast of North America it is stated to 
occur but seldom. 
The small teeth and fine gill-rakers of the Pearl- 
side show that it lives on minute animals. These con- 
sist principally, we may assume, of the small crusta- 
ceans (Entomostraca) that are so abundant in high 
northern latitudes', and which compose the chief food 
of the Herring too, though the latter, as we have seen, 
also preys, like Argyropelecus Olfersii, on the Pearl-side. 
During winter, when the Pearl-side appears in such 
numbers off the Scotch coast, Day examined its gene- 
rative organs, and found the comparatively large eggs 
and the milt almost ripe in February. We may hence 
conclude that the spawning is performed in spring. 
Subfamily S A ( i! I N ffE. 
Body of only slightly irregular Herring- form, or more terete and elongated. Ventral margin more or less terete. 
Cleft of the mouth large and horizontal or only slightly ascending. Inter maxillaries extending to the termination 
of the margin of the upper jaiv. Teeth in the mouth of fairly uniform size. Preabdominal length less than the 
post abdominal. Snout shorter than the postorbital part of the head. 
By. the more forward situation of the ventral fins | ceding ones, so far as regards the general rules for the 
and the greater elongation of the intermaxillaries this J development of the Teleosteous type in these respects, 
subfamily is raised to a higher rank than the two pre- But in the first-mentioned character these fishes come 
“ Trybom found a Pearl-side about 7 cm. long in the stomach of a female Herring measuring 311 mm. that was taken in a drift- 
net off Vinga on the 8th Sept., 1885. 
6 See Day, 1. c., p. 51. 
c Collett also found in the stomach of the Pearl-side Ualanus fnmarchicus. 
Scandinavian Fishes. 
118 
