544 
SCANDINAVIAN FISHES. 
coloration (though also in form) and habits. Their ap- 
pearance resembles that of the Mackerel or Sand-eel, 
with a silvery lustre on the sides. The first dorsal fin, 
like the barbels, develops comparatively late; but the 
ventral fins are long, though with few rays and with 
the outer part black, in the early stages. The forepart 
of the body and the head are laterally compressed, and 
sometimes, according to Lutken, each of the temples is 
furnished with two spines. The eyes are as usual com- 
paratively large in these young specimens, which, how- 
ever, possess the characteristics of the genus. During 
the summer-months they live in companies or shoals 
at the surface, and are often cast ashore or into the 
fishing-boats by the waves. They are also eagerly de- 
voured by sea-birds and fishes-of-prey. The older spe- 
cimens keep to the bottom, leading a more solitary life 
and hiding themselves under rocks, stones, and seaweed, 
or roving about on the clayey bottom. The older spe- 
cimens are remarkably tenacious of life, while the fry 
die almost as soon as they are taken out of the water. 
All these differences, which also vary in their duration, 
one example of a species retaining a, juvenile character 
longer than another, gave rise to the establishment of 
a distinct genus, Concilia", to receive the young forms, 
an error which was first corrected by Malm h and sub- 
sequently by Lutken". 
The genus Onos contains 10 known species d , one 
from Japan, one from the south of the Indian Ocean, 
seven from the Atlantic, the Arctic Ocean, and the 
Mediterranean, and one from the Mediterranean alone. 
The species which belong to the Scandinavian fauna 
may be distinguished as follows: 
A: Longitudinal diameter of the eyes more 
than 30 % of the postorbital length of 
the head. A single barbel at the very 
tip of the snout Onos cimbrius. 
B: Longitudinal diameter of the eyes less 
than 30 % of the postorbital length of 
the head. 
a: Length of the head, even after the 
Concilia- stage, more than 23 % of that 
of the bodyL Margin of the snout 
furnished with several pairs of barbels Onos septentrionalis. 
b: Length of the head, after the Couchia- 
stage,less than 23% of that of the body. 
a: Length of the lower jaw more 
than half that of the head. Tip 
and margin of the snout without 
barbels __ Onos tricirratus. 
(■}: Length of the lower jaw less than 
half that of the head. Tip of the 
snout furnished with a pair of 
barbels Onos mustela. 
THE FOUR-BEARDED ROCKLING (sw. fyrtommade sicarlangan). 
ONOS CIMBRIUS. 
Plate XXVII, fig. 1. 
Four barbels: one at each of the anterior nostrils, one on the tip of the snout , and one on the chin. Length of 
the head in full-grown specimens ( after the Couch ia- stage) less than 20 % ( about 17 — 19 %) of that of the body. 
Longitudinal diameter of the eyes more than 30 % ( about 32 — 40 %) of the postorbital length of the head, which 
is less than the distance between the tip of the snout and the hind extremity of the maxillary bones. 
Length of the lower jaw at least Vs (5 # — 61 %) of that of the head. 
E. hr. 7; D. 45 — 51 0 A. 39—43?; P. 15 — 17; V. 5—6; 
C. 30—31; Vert. 52(57*). 
Syn. Gadus cimbrius, Lin., Syst. Nat., ed. XII, tom. I, p. 440; 
Strussenfelt, Vet.-Akad. Handl. 1773, p. 22, tab. 2, fig. A; 
Bl. Schn. ( Enchelyopus cimbricus ), Syst. Ichth., p. 50, tab. 
9; Betz. {Gadus), Fn. Suec. Lin., p. 323; Nilss. ( Mot ell a ), 
Prodr. Ichth. Scand., p. 48; Schagerstr., Physiogr. Sallsk. 
Tidskr., p. 302; Parn., Mem. Wern. Nat. Hist. Soc., vol. VII, 
p. 449, tab. XLIV; Kr., Damn. Fiske, vol. II, p. 198; 
Ekstr., Gbgs, Vet., Vitt. Samh. Handl., Ny Tidsf., H. I, p. 
a Called Ciliata by Couch (Loud. Mag. Nat. Hist. vol. V, p. 15), and subsequently altered to Coucliia by Thompson {Nat. Hist. Irel ., 
vol. IV, p. 190). 
b Skand. Naturf. M. Kblivn 1873, Ber., p. 384; Gbgs, Boh. Fn., p. 495. 
c Vid. Meddel. Naturh. For. Kblivn 1881, p. 239. 
d Besides these Gunther has described Onos macroplitlialmus (from 80 — 90 fathoms, off the Hebrides) and Onos Carpenter i (from 180 
fathoms, between the Shetland and Faroe Islands), young, three-bearded Rocklitigs, of each of which only one single specimen is known. 
e In the Mediterranean, according to Moreau, Onos tricirratus may also possess this character. 
I 53, according to Storer. 
? 48, 
h According to Malm. 
