552 
SCANDINAVIAN FISHES. 
To judge by these materials, Chios fuscus must, therefore, be 
regarded as the type of the lowest stage of development among the 
Three-Bearded. Rocklings, from which stage each of the other species 
has adopted a distinct direction; and the intermediate position men- 
tioned above finds a natural explanation in the community of characters 
that must be more and more pronounced, the nearer the forms which 
have the same origin, approach to the common original form. As this 
development of form helps us considerably to a correct understanding of 
the characters incident to our Three-Bearded Bockling, we here give, in- 
stead of a more lengthy description, the following table of measurements : 
Length of the body expressed in millimetres 
Length of the head-- in % of the length of the body 
Longitudinal diameter of the eyes „ „ „ „ „ „ „ „ 
Least breadth of the inter.orbital space „ ,, „ „ „ „ „ ,, 
Length of the upper jaw ,, „ „ „ ,, „ „ ,, 
„ „ ,, lower „ „ „ „ „ „ „ „ ,, 
Postorbital length of the head - ,, ,, „ „ „ „ ,, „ 
Distance between the first dorsal fin and the tip of the snout „ „ „ „ „ „ ,, „ 
„ „ ,, second „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 
Base of the first dorsal fin „ „ „ „ „ „ „ „ 
„ „ „ second „ ,, „ „ „ ,, „ ,, ,, ,, 
Length of (he first ray of the first dorsal fin „ ,, ,, „ ,, „ ,, „ 
„ „ „ longest „ „ „ second „ „ „ „ „ „ „ „ „ ,, 
„ ,, „ pectoral fins „ „ „ ,, ,, ,, ,, „ 
„ „ ,, ventral „ „ „ „ „ „ „ „ „ 
Distance between the ventral fins and the beginning of the anal fin... „ „ „ ,, „ „ „ „ 
„ „ ,, anal fin ,, ,, tip of the snout ,, „ „ „ „ ,, ,, „ 
Base of the anal fin — „ „ „ „ ,, „ „ „ 
Longest ray of the anal fin „ ,, „ „ „ ,, ,, „ 
Least depth of the tail „ „ „ ,, „ „ „ „ 
Length of the middle rays of the caudal fin „ ,, ,, „ „ „ „ ,, 
Depth of the body at the beginning of the anal fin „ ,, „ „ ,, „ „ „ 
Greatest breadth of the head „ „ ,, „ ,, ,, „ ,, 
Number of rays in the pectoral fins. 
„ ,, „ „ „ ventral „ 
Onos fuscus. 
Onos mediterraneus. 
Onos tricirratus. 
-*0 
=3 
<rs k - 
w 5 
1. ^ 
p 00 
Algiers 
Locality un- 
known, from 
the Paykui.l 
Collection. 
Average in 
3 specimens 
from Nice. 
w 
9q 
p 
q. 
Island-belt of 
Gothenburg. 
1G4 
176 
189 
232 
246 
208 
360 
430 
20.1 
18.7 
18.5 
19.o 
19.5 
20.9 
20.8 
22.5 
3.0 
2.8 
2.7 
2.i 
3.0 
2.8 
2.5 
2.3 
4.o 
4.o 
3.2 
3.4 
3. i 
4.6 
4.7 
5.i 
10.4 
9.8 
9.2 
9.5 
9.7 
11.2 
ll.i 
13.o 
11.3 
10.2 
10.6 
10.8 
11.0 
12.2 
11.9 
13.2 
12.4 
12.i 
12.2 
12,o 
11.8 
12.9 
12.8 
13.7 
17 a* 
17.5 
17.o 
17.6 
18.3 
19.7 
20.3 
21.i 
31.4 
30.i 
32.3 
33.2 
33.7 
31.6 
30.6 
32.5 
12.i 
12.2 
13.2 
13.i 
14.o 
11.3 
10. o 
10.5 
52.4 
55.7 
55.o 
55.2 
52.4 
56.4 
55.8 
55.i 
4.9 
5.7 
5.3 
4.7 
4.9 
3.6 
2.i 
2.8 
9.i 
8.5 
9.o 
7.3 
8.3 
8.o 
8.o 
— 
10.6 
11.9 
ll.i 
11.0 
10.8 
12.6 
11.9 
14.9 
11.6 
13.6 
14.5 
12.9 
13.3 
18.3 
13.3 
15.3 
30.5 
25.6 
29.6 
30. o 
30.5 
30.3 
26.7 
26.7 
46.3 
42.0 
44.4 
44.4 
45.9 
46.5 
44.2 
44.2 
38.i 
42.6 
42.3 
39.2 
41.o 
40.i 
43.5 
40.7 
6.6 
6.8 
8.4 
— 
7.o 
6.0 
0.4 
— 
4.9 
5.2 
4.7 
5.2 
5.4 
6.i 
6.9 
7.8 
10.4 
10.2 
10.6 
9.9 
9.8 
10.7 
10.i 
10.5 
12.8 
14.5 
13.2 
12.5 
14.4 
12.5 
14.o 
16.3 
11.6 
11.4 
9.5 
10.8 
9.7 
10.9 
12.2 
— 
15 
14 
15 
15 
16 
20 
21 
19 
6 
6 
6 
7 
6 
7 
7 
7 
The Three-Bearded Rockling is the largest Scandi- 
navian species of this genus, and attains a length of 
about half-a-metre. Like the preceding species, it is 
also one of the most typical species of the genus, with 
low and broad snout, the tip of which is naked, as the 
scales of the head do not extend further forward than 
to the line between the anterior nostrils. The posterior 
nostrils are set nearer to the anterior ones than to the 
eyes — sometimes rather near the former — and are 
without any dermal flap, or have the margin evenly 
raised into a short tube. The cards of teeth in the 
jaws and on the head of the vomer are broad and com- 
plete. In young specimens the jaw-teeth are of uni- 
form size, but in older ones fairly large canines ap- 
pear, especially in front in the outermost row of the 
intermaxillary teeth, and at the middle of the inner- 
most row in the lower jaw. The card of teeth on the 
head of the vomer forms a more or less acute angle, 
the sides of which run parallel to the intermaxillary 
bones, and occupies a space in the palate the breadth 
of which is greater than the longitudinal diameter of 
the eyes. The lower margin of the preorbital bones is 
without barbels, but, especially in old specimens, we 
often find this margin undulating in a manner that 
reminds us of the most rudimentary lateral barbels in 
the preceding species. The lateral line runs in a hori- 
zontal direction rather near the dorsal margin back to 
the 9th or 10th pore, below the anterior part of the 
second dorsal fin, at which point it descends, reaching 
the middle of the sides at about the 14th pore, and 
then running straight back, but disappearing on the 
hind part of the tail. Altogether we find 26 or 27 
distinct pores in the lateral line on each side of the 
body. Among the internal organs the air-bladder is 
