SCAD. 
87 
below the isthmus to that on the other side. There 
are 7 curved, branchiostegal rays on each side of the 
body. The body is covered with small, thin, oval scales 
of different sizes, and only the tins, the caudal fin ex- 
cepted, the snout and the lower jaw are naked. The 
smaller scales of the body grow even between the pla- 
tes of the lateral line, especially in the front part. The 
lateral line begins at the upper margin of the gill- 
opening, then runs in an almost imperceptible upward 
curve to a point vertically above the vent, where it 
forms a downward curve, and is then continued in a 
straight line to the base of the caudal tin. It is com- 
pletely covered by about 7 5 transverse plates. Of these 
plates the anterior ones, from the beginning of the line 
to its curve at the end of the pectoral tins, are smooth ; 
but from this point they are furnished with a high, sharp 
keel, which ends behind in a strong spine. The height 
of the keel gradually increases and hence the tail is 
twice as broad as high at the end of the dorsal tin. The 
number of spinous plates is from 35 to 38. These keels 
may be traced even in the skeleton by the hook on 
each side of the last caudal vertebra. The vent is 
about half-way between the tip of the snout and the 
middle of the base of the caudal tin, or a little in 
front of (sometimes at) the middle of the body®. 
The anterior dorsal tin begins with a spine point- 
ing forward and often covered by the skin, vertically 
above the insertion of the ventral fins, and ends above 
the vent. It is short and high, with 8 unarticulated, 
but weak, rays. The posterior dorsal tin is long, ends 
above the end of the anal tin and generally contains 
from 30 to 33 rays. The first of these is unarticulated 
and half as long as the second, which, like all the 
others, is branched and articulated. The pectoral tins 
are narrow, falciform and equal in length to the head. 
They each contain 19 or 20 rays, the two uppermost 
undivided and the top one of all unarticulated, the 
others branched oftener and oftener to the lower side 
of the tin. The ventral tins are long and pointed, ex- 
tending almost to the vent. In form the anal tin is 
like the second dorsal. It generally contains 28 or 29 
rays, the first of which is unarticulated. In front of 
this fin is another smaller one, with only two, small, 
spinous rays, which are joined by a membrane. The 
caudal tin is crescent-shaped, with 18 or 19 long rays, 
the two outer ones being undivided; there are also 4 
or 5 smaller (rudimentary) rays at the top and bottom 
of the base. 
The colour of the back is dark olive-green with 
lighter, wavy, transverse bands. The head and the 
sides below the lateral line silver with a dash of orange, 
like mother-of-pearl. The iris silver-white, the pupil 
dark blue. The interior of the mouth black like the 
inner side of the branchiostegal membrane, which is 
edged with silver. A large black spot at the upper 
margin of the gill-opening. The anterior dorsal fin 
transparent, the posterior dark gray, as is also the 
caudal: the other tins white. 
The interior of the abdominal cavity is dark in 
colour, the liver pale red, large and bilobate, and the 
spleen large and triangular. The kidneys are black 
and of average size. The intestinal canal bends twice. 
The stomach is large and there are a large number 
of pyloric appendages (from 12 to 20, according to 
Gunther). The ovaries are large, but the eggs small. 
The food of the Scad consists of small fry and 
crustaceans. The most usual contents of the stomach 
are young Herrings, Sprats, or Sand-launces. It occurs 
in the Cattegat all along the coast of Bohuslan and is 
by no means rare, but is always taken singly. Ekstrom 
never found it in shoals, as it lives in other places, 
and could never hear of its being so found. According 
to Nilsson, it has, in addition to the name given here, 
those of tag g sill and, off Kullen, stag g sill and staksill h . 
Malm says that in Bohuslan it is called piggmakrel 
(Picked Mackerel) and sJcrej, while Cederstrom also 
gives the name of silfverfisk (Silverlish). 
The Scads which are caught by whiffing (Sw. rann- 
dorj — - running-line) during the Mackerel-fishery in 
Bohuslan, at the beginning of June, have ripe roe in 
the ovaries. It may therefore be assumed that the 
spawning-season occurs in this month, though no place 
is known where this fish spawns. Most probably it 
does so out at sea. That it really does spawn in the 
Cattegat, is proved by the occurrence there of the fry, in 
company with the large jelly-fish ( Cganea capillata ) so 
common there, of which it seems to be a sort of para- 
site c . The fry stay under the body of the jelly-fish, 
among its ovaries, and seem to feed exclusively on its 
eggs. This most remarkable habit was first observed by 
“ In Todd’s figure (Brown-Goode, 1. c.) the vent is situated considerably in front of the middle of the body. 
b All three names are about equivalent to ‘Spiny-Herring’. Tr. 
c Malm (1. c.) also found the fry in Rliizostoma Aldrovandi. 
