346 
SCANDINAVIAN FISHES. 
fold, black at the margin, which strongly reminds us 
of the corresponding growth in the true Hemircimphi a . 
Here this fold disappears during growth, though in 
specimens 60 mm. long it is still present, but stunted. 
The following changes in the shape of the snout and 
the length of the lower jaw are represented in the 
figures. In specimens about 60 mm. long the head is 
roughly of the shape shown in fig. y in the woodcut. 
It still resembles that of Hemira mplms : the front angle 
of the snout has passed from obtuse to right and fi- 
nally fo acute; but the tip of the snout is now marked 
off from the sides by a little sinus on each side: this 
Fig. 92. Postembryonic changes of growth in the heads of Scombre- 
sox and Ramphistoma. After Lutken. Figs, a — h of Scombresox 
saurus; cc — £ of Ramphistoma belone. a magn. 3 diam.; b l / 5 more 
than the natural size; c and d */, more than the natural size; e b- 
more than the natural size. / 1 /„ less than the natural size; g 1 / 3 
less than the natural size; h 1 / 4 less than the natural size, a — 4 
magn.; £ less than the natural size. For further explanation 
see the text. 
is the beginning of the elongation of the upper jaw, 
and while this proceeds, teeth appear in that part of 
the lower jaw that corresponds to the upper. In spe- 
cimens about 70 mm. long the head is of the shape 
shown in fig. d in the woodcut; and in specimens about 
150 mm. long the snout has assumed the shape typical 
of the Gar pikes, though the upper jaw is still con- 
siderably (about three times the diameter of the eye) 
shorter than the lower. In full-grown Garpikes the 
difference in the length of the jaws is only equal to 
or 1 / 3 less than the diameter of the eye. 
The development of the fins presents the usual 
changes, but interests us by a characteristic peculiarity, 
the persistency of a part of the embryonic (larval) ver- 
tical fin and the late appearance of the ventral fins. 
Even in a young Garpike 15 mm. long this vertical 
fin is still present at the lower caudal margin, between 
the anal and caudal fins: between the dorsal and caudal 
fins it has disappeared; but at the ventral margin, from 
the vent to the end of the first third of the length of 
the abdomen, a great part of it, measuring more than 
half the depth of the body at this point, is still per- 
sistent. As yet only the caudal fin, which is of a 
rounded shape, contains distinct rays. In the anal fin, 
the anterior part of the dorsal fin and the upper part 
of the pectoral fins, which are lobafe (furnished with 
a semi-elliptical basal part) and round, more or less 
distinct rudiments of the true rays now begin to form; 
but the remainder of each of these fins is supported 
by the primary fibrillse alone. Not a trace of the 
ventral fins is externally visible, with the exception of 
a light, round spot on each side of the base of the 
vertical abdominal fin, the distance between it and the 
vent being scarcely 1 ,/ 3 of the length of this fin. This 
spot forms a scarcely perceptible contrast to the rest 
of the surface of the body, which is thickly strewn 
with blackish green collections of pigment*. At these 
points the ventral fins appear first in the form of small 
protuberances, which assume a lobate form. But, even 
in specimens 25 V 2 mm. long — where the vertical ab- 
dominal fin is still almost unchanged, and the pigmental 
spots on the body still present — the ventral fins appear 
almost as microscopical lobes. In specimens 53 mm. 
long distinct traces of the vertical abdominal fin are 
still present, but the pigmental spots on the belly and 
the lower part of the sides have begun to disperse, 
and to give place to the incipient silvery lustre. The 
ventral fins are even now scarcely more than half a 
millimetre long, while the length of the pectoral fins 
is fully 3 mm. or exactly equal to the postorbital 
length of the head. 
a See Beeeker, Atl. Ichth. Ind. Neevl., pp. 53 etc., tab. Scombres. IV, VI — VIII. 
b On the upper part of the body these spots are set in fairly regular longitudinal and oblique transverse rows, the former being 
especially distinct at the middle of the back. On the lower part of the body they are irregularly arranged in longitudinal rows, and they 
are wanting only on the under surface of the head and of the front part of the belly, as well as on the operctila. 
