1124 
SCANDINAVIAN FISHES. 
ments of these parts, the variations in this respect are 
equally great in the two species and overlap each other. 
The spiny armature of the skin is generally weaker 
and on the dorsal side sparser than in the common Skate 
— sometimes it is entirely wanting — but on the ventral 
side it is more uniform and more extensive, except at 
the outer margins of the ventral tins and on the tail, 
which in some instances, however, has a strip of tine 
spinulse along the middle of its under surface. The aculei 
of the young are persistent, at least in the males, on 
In a male 1 4 3 / 4 dm. long the length of the head 
to the occiput measured 27'8 %, that of the snout from 
the anterior margin of the eyes 21 %, and the distance 
between the mouth and the tip of the snout 22 ‘3 %, of 
the length of the body. The last-mentioned distance 
was 68 % of that between the mouth and the cloaca! 
aperture, a percentage which, according to Collett’s 
figure, amounts in a female 19 dm. long only to 56. 
The breadth of the mouth was 40 % and the internasal 
width 45'8 % of the length of the snout". The jaw- 
Fig. 324. Black-bellied Skate ( Raja nidrosiensis), ok from Trondhjem Fjord, March 17, 1891. Conservator Storm. 1 / 1 0 nat. size. 
The skeleton of this specimen is figured above, p. 1064. 
the orbital margins, and are also retained in both sexes 
on the upper median line of the tail, a few usually re- 
maining as well between the two dorsal fins; but ac- 
cording to Collett only the females are furnished with 
a row of aculei on each lateral margin of the tail. 
" According to Collett’s figure the last-mentioned percentage 
to have been even narrower than that of the specimen described abov 
b The distinction adduced by Moreau between the dentition: 
of age and sex. 
c According 1o Carus Raja macrorhynchus is also dark brown 
teeth are similar to those of the common Skate both 
in number and form b . 
The coloration of the dorsal side, according to Col- 
lett, is of a dark grayish brown, and the ventral side 
is nearly brownish black, blackest in the middle c . The 
amounts in a female 19 dm. long hardly to 37; and the mouth seems 
e. 
3 of Raja macrorhynchus and R. batis evidently depends on differences 
{fused) both above and underneath. 
