584 
SCANDINAVIAN FISHES. 
thin osseous ridges, and projects more or less beyond 
the month, which is forced downwards to the lower 
surface of the head, like that of a shark. Thus, great 
as the dissimilarity is between the extreme forms of 
the snout in the species of Macrurus , there is no funda- 
mental difference in structure; they merely represent 
different degrees of the same line of modification. 
“With regard to the scales, there is also every 
gradation from the small-scaled Malacocephali to the 
large-scaled Macrurus longibarbis. In very young spe- 
cimens of all species the scales formed at first are al- 
ways thin, without any armature, in fact cycloid. Spines 
appear only after some time, generally in the median 
line of the scale, simply and not in series; scales with 
fully developed armature are generally not found in 
specimens under 8 inches in length. In some species 
which normally possess strongly spiniferous scales, 
individuals may occur (especially such whose skin is 
wanting in pigment), in which the spines are much 
more feeble and scarcely visible. And finally, there 
are species in which the cycloid structure of the scales 
remains normally persistent. Thus, neither the size 
nor the structure of the scales can be safely used as 
a generic character.” 
On the other hand, Gunther fully recognises the 
validity of a character first suggested for this purpose 
by Lutken °, and derived from the presence or absence 
of the spines (set in an upward (backward) direction 
on the front surface of the ray) that arm the second 
(apparently the first) ray of the dorsal fin. Even this 
character is subject to changes of growth, for, where 
these spines are present, in old specimens they may 
become indistinct (tubercular); but they never dis- 
appear altogether. 
The species hitherto discovered within the limits 
of the Scandinavian fauna may be distinguished, ac- 
cording to these opinions, in the following manner: 
A: Jaw-teeth at least in front cardi- 
fonn (or velvet-like); scales middle- 
sized or large. 
1 : Snout pointed; cheeks carinated : 
a: Second ray of the first dor- 
sal fin smooth (unarmed). .. J Macrurus (Coelorhynchus) 
\ coelorhynchus. 
b: Second ray of the first dor- 
sal fiu spiny J Macriirus (Macrurus) 
2: Snout blunt; cheeks almost^ Fabricii. 
even j Macrurus ( Coryphamoides ) 
B: Jaws furnished with canine teeth ^ rupestris. 
set in two rows in the upper jaw, 
in one row in the lower I Macrurus ( Malaco - 
I ceplialus) Ice vis. 
It sometimes happens, however, that the character 
derived from the structure and arrangement of the jaw- 
teeth, employed in this manner, firstly brings together 
forms extremely dissimilar in other respects 6 , and 
secondly is very difficult of employment, for in young 
specimens of the Coryphamoid group, even when they 
are 12 cm. long, it is hardly possibly to discover more 
than two rows of teeth in the upper jaw and one row 
in the lower. Again, several species of Gunthers sub- 
genera Chalinurus and Optonurus have true canine teeth 
in the outermost row of the card in the upper jaw and 
only one row of teeth in the lower jaAv. The folloAving 
classification appears easier and, therefore, more trust- 
worthy. 
A : Least breadth of the interorbital 
space less than the length of the 
snout, than J / 4 of the length of 
the head, or than 3 / 5 of the greatest 
breadth of the head at the perpen- 
dicular from the centre of the eye: 
a: Least breadth of the interorbital 
space more than or equal to 3 /- 
of the length of the lower jaw, 
which is less than 40 % of the 
length of the head Macrurus coelorhynchus. 
b: Least breadth of the interorbital 
space less than 1 / 2 the length 
of the lower jaw, which is more 
than 40 % (44 /?) of the length 
of the head Macrurus Fabricii. 
B: Least breadth of the interorbital 
space greater than the length of the 
snout, and greater than or equal to 1 / , 3 
of the length of the head or 7 /io °f 
its greatest breadth at the perpen- 
dicular from the centre of the eye. 
a: Least breadth of the interorbital 
space more than 4 A of the length 
of the lower jaw... Macrurus rupestris. 
b: Least breadth of the interorbital 
space less than or equal to 3 / 3 
of the length of the lower jaAv Macrurus hvvis. 
a Vid. Meddel. Naturh. For. Kbhvn 1872. p. 4. 
6 Cf., for example, Macrurus Icevis and Macrurus macrocliir. 
