316 
SCANDINAVIAN FISHES. 
Length of the 
body in 
millimetres. 
Greatest depth of the body 
in % of the length thereof. 
Length of the head in % of 
that of the body. 
Distance between the vent and 
the tip of the snout in % of 
the length of the body. 
Track, arcticus. 
Track, iris. 
Track, arcticus ■ 
Track, iris. 
Track, arcticus. 
Track, iris. 
2,035 
19.1 
ll.l 
51.8 
1,312 
18.2 
— 
12.4 
— 
52.9 
— 
991 
17.6 
— 
14.2 
— 
54.8 
— 
923 
— 
12.3 
— 
10.6 
— 
— 
917 
17.5 
— 
14.3 
— 
55.o 
— 
766 
— 
12.8 
— 
10.6 
— 
46.7 
333 
— 
18.i 
— 
13.8 
— 
52.8 
219 
— 
21.0 
— 
16.2 
— 
53.3 
130 
— 
25.7 
— 
21.o 
— 
64.8 
In the last four columns the rise or fall of the numbers is 
common to both species, and we can find no consistent difference in 
any of the three proportions given. Still, it is only in the juvenile 
stages of the latter species that we can find the same proportions as 
in the former. This statement applies, however, only to the averages: 
it is only in the character first given (the depth of the body) that 
the difference is so marked that the character, to the best of our 
knowledge at present, is independent of the individual variations. 
We also see that the direction of development in this case is not 
the same, for the proportion rises with age in the one form and sinks 
in the other, assuming that the rule which holds good in this table 
for Trachypterus arcticus, also applies to the earlier stages of this 
species, which are still unknown. 
The Dealfish attains a length of at least 2 l / 2 metres". 
The ribbon-shaped body * * 6 is of fairly uniform depth for 
the greater part of its length behind the head, but is 
deepest at about the middle of this part c , which ends 
at a varying distance behind the vent. From this point 
the outlines of the body sharply converge, at about equal 
angles upwards and downwards, towards the shallow 
base of the caudal tin' 6 . The back behind the head is 
almost entirely occupied by the continuous dorsal tin 6 , 
the height 7 of which fairly closely follows the lines of 
the body, with the exception of the fact that in front 
it is lower, but steeper, and behind higher than the 
latter. In front of this fin there probably lies in all 
young specimens a- higher occipital or anterior dorsal 
fin, whose 6 (sometimes only 5) raj^s are, however, fra- 
gile, and generally disappear with age externally, though 
their stumps may generally be traced in the dorsal 
edge. Behind the dorsal fin rises the caudal fin de- 
scribed above 7 , sometimes in a vertical direction, but 
sometimes leaning sharply backwards. Of the stunted 
rays of the caudal fin (the original lower part thereof) 
the stumps may generally lie traced without difficulty, 
three above and two below the end of the lateral line, as 
well as the double spine (spinous plate) which is situated 
in front of them, on the under surface of the end of 
the tail, with one point directed forwards and the other 
backwards, and which has replaced the original lowest 
(rudimentary) ray of the caudal fin. The singular ap- 
pearance of the fish is further enhanced by the entire 
absence of the anal fin and, usually, of the ventral fins, 
though the latter, at least in specimens not more than 
a metre in length, generally leave traces behind them 6 
in the form of a row of stumps (from five or less to 
ten) on each side of the ventral margin, just behind 
the perpendicular from the end of the horizontal base 
of the pectoral fin. The pectoral fins are turned up- 
° The largest specimen from Norway examined by Collett was 246 cm. long. The occurrence alleged by fishermen of specimens 
3 m. in length has not been confirmed up to the present. 
6 The body, it is stated, becomes considerably thinner after death and on dry land. In the specimens preserved in spirits it is 
thickest at the head, across the upper articulation of the preoperculum, where the breadth measures 3 or 4 % of the length. 
c Even in specimens from 830 to 985 mm. in length, according to Lutken, the greatest depth of the body may be no more than 
15 or 16 % of the length; but it afterwards rises to at least 20 °/o thereof — according to Sparre-Schneider, 21 '4 /. The greatest depth 
usually occurs in front of the vent, but in a specimen about 11 dm. long, from West Fjord (Norway) the body is deepest just at the vent. 
d The least depth of the tail measures only from about 1 to 2 l / 0 % of the length of the body (the latter measurement according to 
Reinhardt). Still, it is so strongly compressed that at this point the thickness (breadth) of the body is only about 1 / 3 of the depth. 
c The roughness of the rays of the dorsal fin, caused by small spines along their sides, is extremely inconstant. Sometimes, especially 
in old specimens, all the rays are smooth to the touch, if we except the basal spine on each side. 
■ T ' The length of the longest ray of the dorsal fin, about the 100th from the beginning, is about half the greatest depth of the body. 
3 In specimens between 830 and 1,505 mm. long the length of the caudal fin varies, according to LDtken, between 18 and 1 1 1 li % 
of that of the body; in a specimen 1,870 mm. long he found the length of the caudal fin to be only 9 % of that of the body. 
h In a specimen 76 cm. long Sparre-Schneider found the stump of the first ray of the ventral fin to measure 43 mm. in length. 
