NORTHERN ROCKLING. 
549 
long. The species is distinguished in the first place by 
its large head and deeply-cleft mouth. The former is 
a character of age, which in this genus as in others 
belongs to the fry, but the latter is of entirely opposite 
signification, the gape being as a rule even relatively 
larger and more deeply cleft in old Rocklings than in 
young. The development of the numerous barbels is 
strictly to be regarded as a variation of the character 
of the Five-Bearded Rocklings, for we find two nasal 
barbels, two rostral ones, and one barbel under the chin, 
all of which in this species, too, are regularly set at 
their fixed places. Besides these, however, we find a 
row of more or less rudimentary barbels, more or less 
pointed, small dermal flaps or small, blunt dermal pro- 
tuberances, situated like the rostral barbels in the der- 
mal fold at the lower margin of the preorbital bones, 
which partly conceals the upper jaw and runs forward 
under the tip of the snout or a little above it. In 
Collett’s type-specimen there are three of these rudi- 
mentary barbels on each side behind the rostral ones, 
but in another specimen he remarked one more barbel, 
situated “straight behind” (above the space between) 
these two barbels. 
The head is distinctly depressed (broader than high: 
the greatest breadth equal to the length of the lower 
jaw). The body is fairly deep in front — in the type- 
specimen the depth at the beginning of the anal fin is 
16 % of the length of the body; but behind the depth 
decreases more rapidly than is usual in the genus, the 
depth of the peduncle of the tail in the type-specimen 
being no more than f> 8 1 / 2 % of the depth of the body 
at the beginning of the anal fin. In all the specimens 
of the other Rocklings that we have been enabled to 
examine, this percentage has been more than 30. 
The eyes are small, their longitudinal diameter 
being about 1 1 1 / 3 % of the length of the head and only 
slightly more than half the breadth of the flat inter- 
orbital space". On account of the depression of the 
head they are turned obliquely upwards (at an angle 
of about 45°), and they lie almost vertically above the 
middle of the length of the upper jaw. The posterior 
nostrils lie somewhat farther from the eyes than from 
the anterior nostrils. The jaw-teeth form cards in the 
ordinary manner, but the teeth in the outermost row 
on the intermaxillary bones and in the innermost row 
in the lower jaw are more scattered and only slightly 
larger than the others. The breadth of the card of 
teeth on the head of the vomer is somewhat greater 
than the longitudinal diameter of the eye, and these 
teeth form an angle rather acute in front. 
In Collett’s type-specimen the distance between 
the first dorsal fin and the tip of the snout is nearly 
23 %, and the base of this fin nearly 9 %, of the length 
of the body. The length of the first ray 6 is about 
equal to the breadth of the interorbital space c or to the 
least depth of the tail C The distance between the se- 
cond dorsal fin and the tip of the snout is 33 V 2 % of 
the length of the body, and its base measures about 
52 % of the same length. The middle rays of the 
rounded caudal fin do not measure quite 1 / 10 of the 
length of the body. The distance between the anal fin 
and the tip of the snout is 46 %, the distance between 
it and the base of the ventral fins 23 %, and the length 
of its base 40 %, of the length of the body. The length 
of the pectoral fins is Vs °f that of the body. The length 
of the ventral fins is contained about 7 J / 2 times in that 
of the body. 
The covering of scales leaves the greater portion of 
the snout naked, but extends forward on the forehead 
to a line with the posterior nostrils. The lateral line 
follows the same course as in the preceding species 
and contains about 20 pores. 
The coloration, according to Collett, is plain 
grayish brown, without spots, slightly lighter on the 
ventral side than on the back. The specimen preserved 
in spirits is reddish brown, with the ventral side shad- 
ing into gray. The inside of the mouth white. The 
iris blackish blue. 
In his last account of the fishes of Norway Collett 
tells us that 9 specimens of this species are known at 
present, from the north and west parts of the Norwegian 
coast, from Ox Fjord in Finmark down to Floro off 
Stadt Promontory. The Museum of Copenhagen pos- 
sesses a specimen from Greenland. The species was 
first discovered in 1873 during Professor Sars’s dredg- 
ing-operations; and of its habits nothing more is known 
than that it is met with in deep water, sometimes at 
least 50 fathoms in depth. 
0 In a younger specimen Collett found the longitudinal diameter of the eyes to be 16 2 > % of the length of the head, and their 
vertical diameter equal to the breadth of the interorbital space. 
& 19'3 % of the length of the head. 
c 20-0 % „ „ „ „ 
d 18-6 % „ „ „ „ „ „ 
