556 
SCANDINAVIAN FISHES. 
all the older specimens the base of the anal tin is greater 
than the distance between this tin and the tip of the 
snout. This is also the case in the Four-bearded Rock- 
ling; but in the young specimen of the Five-bearded 
Rock ling, as well as in the Three-bearded and the 
Northern Rocklings, the base of this tin is less than 
the said distance. The almost uniform size of the jaw- 
teeth in the Five-bearded Rockling is a persistent ju- 
venile character, which this species possesses in common 
with young specimens of the Three-bearded Rockling; 
but the card of teeth on the head of the vomer is 
never so broad in the former as in the latter, although 
it does not undergo so great reduction as in the Four- 
bearded Rockling. 
The Five-Bearded Rockling thus ranks as an inter- 
mediate form between the preceding ones, as Ave have 
above found to be the case with Onos fuscus in its 
relations to On. mediterraneus and On. tricirratus. That 
the original form of the Avhole genus Avas three-bearded 
seems highly probable, as the difference betAveen the 
unpaired and the paired arrangements of the rostral 
barbels, presupposes a stage of development in Avhich 
this difference did not exist. In other respects, hoAV- 
ever, Onos mustela forms a connecting link betAveen 
the tAvo directions of development, and may, therefore, 
in all probability be regarded, to the best of our knoAV- 
ledge, of the genus in its present arrangement, or at 
least of the North Atlantic and the Mediterranean spe- 
cies, as the least differentiated (most nearly original) 
type Avithin the genus. 
In the Five-Bearded Rockling the coloration is of 
a more or less dark reddish broAvn or even olive-green 
on the dorsal side, light grayish, Avhite, yelloAvish, or 
sometimes reddish on the belly, without any sharp line 
of demarcation and Avithout true spots. Sometimes, 
hoAvever, Ave find indistinct, clouded spots on the sides, 
caused by the denser agglomeration of the line, dark 
broAvn dots that are scattered over the Avhole body. 
The sides of the body shoAV a metallic — or silvery — 
lustre. The second dorsal tin at the base is of the 
same colour as the back, the anal fin as the belly, but 
the outer and especially the posterior parts of these fins 
are blackish. The pectoral fins are also blackish, but 
of a more or less distinct orange at the base. At the 
extreme margin all these fins are usually edged Avith 
red. The nasal and rostral barbels are of the same 
colour as the dorsal side or still darker, the barbel 
under the chin of the same colour as the belly. 
During life the ventral fins are reddish (Hollberg), 
or have “orange rays, Avith Avhitish-yelloAV membrane” 
(Schagerstrom). The “small black dots Avhich are 
set in oblique toavs across the sides” (Hollberg), are 
the pigmented dermal coverings of the several scales, 
an ordinary characteristic of the Avhole of this genus, 
Avhich statement also applies to the fine, dark broAvn 
dots that are scattered over the body. In a live young 
specimen 78 mm. long Collett found the pupil to be 
of a handsome emerald-green, and the iris red, Avith a 
metallic lustre. 
In the fry ( Concilia glauca — Plate XXVII, fig. 3), 
Avhich have been most fully described, under the name 
d p 
v 
Fig. 133. Young - Onos. 6 mm. long, with projecting lower jaw. 
After M’Intosh and Prince, p , pectoral fin; v , ventral fin; d and c, 
the still confluent dorsal and ano-caudal fins. 
of Motella argenteola, by v. Duben and Koren, the 
back is bluish green doAvn to a level Avith the upper 
corners of the gill -openings, and forms a sharp contrast 
to the Avhite, silvery lustre of the sides. All the fins 
are transparent and Avhite, except the ventrals (tig. 134), 
the black tip of Avhich groAvs more and more indistinct, 
d p 
Fig. 134. Young Onos. 10 mm. long, with black tip to the ventral 
fins. After M’Intosh and Prince, p, pectoral fin; v, ventral fin; 
d, dorsal fin; c, caudal fin. 
hoAvever, as the fins are shortened during groivtli, and 
their insertion removed further and further fonvard, 
until in specimens about 25 mm. long these fins are 
also pure Avhite. The development is subject to extreme 
variations; but the scales do not appear until the fish 
is about 38 mm. long, Avhile the strong, silvery lustre 
is still persistent, until the fish has attained a length 
of 40 — 45 mm., and even then, as Ave have remarked 
above, does not disappear entirely. On the other hand, 
the dermal carina that runs on each side of the back 
from the end of the first dorsal fin along the base of 
the second dorsal, as Avell as the similar carina on each 
