FOUIl-BEARDED ROCK LI N G . 
545 
39; Nilss., Skand. Fn., Fisk., p. 587; Gthr, Cat. Brit. 
Mus., Fish., vol. IV, p. 367; Lindstr., Gotl. Fisk., Gotl. 
L. Hush. Sallsks. Arsber. 1866, p. 21 (sep.); Mgrn, Ofvers. 
Vet.-Akad. Fork. 1867, p. 263; Coll., Forh. Vid. Selsk. 
Christ. 1874, Tillajgsh., p. 116; ibid. 1879, No. 1, p. 67; 
Malm, Gbgs, Boh. Fn., p. 498; Wintii., Naturh. Tidskr. Kbhvn, 
ser. 3, vol. XII, p. 33; Ltkn, Vid. Meddel. Naturh. For. 
Kbhvn 1881, p. 235; Day, Fish. Gt. Brit., Irel., vol. I, p. 
316, tab. LXXXIX, fig. 1; Jord., Gilb. ( Onos ), Bull. U. S. 
Nat. Mus., No. 16, p. 797; Mob., IIcke ( Motella ), Fisch. 
Osts., p. 83; Storm, Norsk. Vid. Selsk. Skr. Trondhj. 1883, 
p. 36; Lillj. (Onos), Sv., Norg. Fisk., vol. II, p. 175; 
Hansen, Zool. Dan., Fiske, p. 85, tab. X, fig. 5. 
Gadus Mustela, Strussenf., 1. c., p. 24, tab. II, fig. B. 
Motella caudacuta , Stor., Proc. Bust. Soc. Nat. Hist., vol. Ill, 
p. 5; Mem. Amer. Acad. Arts, Sc., n. ser., vol. VI, p. 361, 
tab. XXIX, fig. 1 ; Gill ( Rhinonemus ), Proc. Acad. Nat. Sc. 
Philad. 1863, p. 241. Cf. Goode et Bean, Proc. U. S. 
Nat. Mus. vol. 3 (1878), p. 348. 
Couclna Edwardii, Couch, Journ. Lin. Soc., Lond., Zool., vol. 
IX, p. 38. 
In Scandinavia, according to Lilljeborg, the Four- 
Bearded Rockling sometimes attains a length of about 
41 cm."; but its usual length varies between 20 and 
38 cm. The largest specimen ever taken on the coast 
of Great Britain was 35 cm. long, according to Day. 
In adult specimens the form of the body is compara- 
tively elongated, this species being generally the most 
slender of our Rocklings, and the depth at the begin- 
ning of the anal tin measuring on an average only about 
12 % of the length of the body. According to the rule 
of the generic changes of growth, however, this pro- 
portion increases with age, after the Couchia-stage, and 
may sometimes be nearly as much as 14 %. The least 
depth of the body, in front of the base of the caudal 
fin, varies between 37,2 and 4 7 2 %, or eventually nearly 
5 %, of its length. Even in front too, the body is only 
slightly terete. The head is generally somewhat de- 
pressed — all these remarks apply to adult specimens — 
but its section is sometimes nearly square. At the be- 
ginning of the second dorsal fin the thickness is about 
3 / 4 or 3 / 5 of the depth; and posteriorly the thickness 
decreases more and more, measuring at the beginning 
of the anal fin about 2 / 3 or 1 / 2 of the depth. The extreme 
end of the tail is almost ribbon-shaped. The elongated 
form of the body is further enhanced by the comparatively 
great length of the caudal fin, the middle rays of "which 
measure more than the postorbital length of the head. 
The points in the form of the head that are cha- 
racteristic of this species, are the depth of the snout, 
the size of the eyes, and the comparative narrowness of 
° Winther mentions a specimen from Liim Fjord of a length 
or by Hansen, and is probably due to a slip of the pen or an error 
the head itself. With its tumid cheeks (thick mastica- 
tory muscles) and when the gill-covers are expanded, 
the head is broad and may be called depressed; but, 
until the fish has attained a length of about 3 dm., the 
breadth of the head is less than half Its leno;th. The 
quadrilateral, more or less square form of the transverse 
section of the head is persistent in the snout, at least 
for a lengthy period, though in old specimens it finally 
becomes more depressed. Simultaneously with this 
change of growth the position of the eyes is also altered. 
Originally they are quite lateral, set vertically and pa- 
rallel to each other, but they eventually acquire a some- 
what upturned position and diverge backwards. The tip 
of the snout projects beyond the upper lip and the still 
shorter lower jaw, and the length of the snout is on an 
average 1 / 4 of that of the head. The eyes are oblong, 
their longitudinal diameter measuring on an average 
1972 % °f the length of the head. The nostrils are set 
on the sides of the snout, on about a level with the 
centre of the eye, the anterior pair rather near the be- 
ginning of the sharply rounded tip of the snout, the 
posterior half-way between the tip of the snout and the 
eyes. The barbel projecting behind each of the anterior 
nostrils extends,, when laid back, at least to the centre 
of the eye and sometimes even a little behind the eye. 
The unpaired barbel is the shortest, measuring only 
about half the longitudinal diameter of the eye. The 
barbel under the chin is somewhat longer, but measures 
less than the length of the eye. We must remember, 
however, that during life these barbels, as well as the 
fleshy lips, are very mobile, and the unpaired barbel is 
said to be capable of elongation and retraction, like the 
tentacles of a mollusk. The mouth is rather large, its 
corners lying in old specimens vertically below the hind 
margin of the eyes, and the maxillary bones extending 
back to a distance from the tip of the snout that is 
always more than half (about 53 7 2 — 62 %) of the length 
of the head. The length of the lower jaw is always 
less than this distance, and varies with age between 50 
and about 59 % of the length of the head. The post- 
orbital part of the head is generally longer than the 
lower jaw, but shorter than the distance between the 
tip of the snout and the hind extremity of the max- 
illary bones. Its length seems to be more subject to 
individual variations, and measures between 527 2 and 
577 2 % °f the length of the head. The gill-openings 
of 63 cm. This statement is not confirmed, however, either by Lutken 
•>f the press. 
Scandinavian Fishes. 
69 
