POLE-FLOUNDEK. 
379 
98; ibid. 1879, No. 1, p. 82; Norsk Nordh. Exp., Zook, 
Fiske , p. 150; Malm ( Pleuronectes ), Gbgs, Boh. Fn., p.527; 
Winth., Naturh. Tidskr. Kbhvn, ser. 3, vol. XII, p. 40; 
Goode, Bean ( Glyptocephahis ), Proc. U. S. Nat. Mus. vol. 1 
(1878) p. 19; Hanssox, Ofvers. Vet.-Akad. Forh. 1880, 
No. 4, p. 52; Mor. ( Platessa ), Hist. Nat. Poiss. Fr., tom. 
Ill, p. 296; Jord., Gilb. ( Ghjptocephalus ), Bull. U. S. Nat. 
Mus., No. 16, p. 838; Day ( Pleuronectes ), Fish. Gt. Brit., 
Irel., vol. II, p. 30, tab. C1II; Mob., Hcke, Fisch. Osts., 
p. 99; Lillj., S’v., Norg. Fn., Fisk., vol. II, p. 386; Gthr, 
Voy. Chall., Deep-sea Fish., p. 166. 
Pleuronectes Satcicola, Faber, Tidskr. f. Naturv., Bd. 5 (1828), 
p. 244; Isis 1828, p. 877; Gottsche ( Glyptocephalus ), 
Wiegm. Arch. Naturg., Bd. I, part. 2, p. 156; Kr. {Platessa), 
Damn. Fiske, vol. 2, p. 338. 
Pleuronectes nigromanus , Nilss., Prodr. Iclith. Scand., p. 55; 
Schagerstr., Physiogr. Sallsk. Tidskr., Heft. 2, p. 312; 
Valenc. apud. Gaim, Voy. Isk, Groenk, Poiss., tab. 13. 
Platessa pola, Jenyns, Man. Brit. Anim., p. 458, sp. 145; 
Yarr., Hist. Brit. Fish., ed. 2, vol. II, p. 315; Thomps., 
Nat. Hist. Irel., vol. IV, p. 197; A. Agass . {pole flounder) 
Bull. Mus. Comp. Zool., Harv. Coll., vol. XV, p. 24. 
Platessa elongata, Yarr, 1. c., p. 318; Gthr ( Pleuronectes ), 
1. c., p. 450; Day, Proc. Zool. Soc. Loud. 1879, p. 755, 
tab. LXI; Gill ( Glyptocephalus ), Proc. Acad. Nat. Sc. Philad. 
1873, p. 362. 
Glyptocephalus acadianus, Gill, 1. c. (vide Goode et Bean, 
1. c.). 
The elongated (narrow elliptical) and thin shape 
of the body, the large number of rays in the dorsal 
and anal fins, the cavities in the head (especially on 
the blind side), and the black colour of the outer half 
of the pectoral fin on the eye side, all combine to 
render the Pole easily recognisable and to explain the 
name it bears in the island-belt of Gothenburg ( Jyde - 
tunga — Jutland Sole). In Scandinavia it attains a 
length of at least half a metre, while American speci- 
mens about 62 cm. long are on record. The greatest 
depth of the body, which undergoes even relative in- 
crease with age, in adult specimens measures on an 
average J / 3 of the length of the body, but sometimes" 
sinks as low as 1 4 thereof. The males of this species 
are probably, as a rule, no more elongated than the 
females * * 6 . Behind the head the body grows thinner 
and thinner posteriorly. The Danish fishermen, accord- 
ing to Gottsche, call this species on account of its 
transparency Spindelflynder^ Spider (Cobweb) Flounder. 
The greatest thickness of the head, straight across the 
upper articulation of the preoperculum, measures only 
about V 3 of its length. 
In this species, as well as in the next one, the 
head is smaller than in the rest of our Flatfishes; but 
in the Pole it is remarkable chiefly for the large ca- 
vities which here, as in Acerina cernua, are formed by 
the muciferous hollows of the system of the lateral line. 
These cavities are most distinct and largest on the blind 
side. Here there are four round cavities in a row close 
to the dorsal margin and belonging to the occipital 
branch of the lateral line on this side; while below 
these there generally lie five cavities, belonging to the 
frontoparietal and suborbital branches, four of them in 
a curved row and the fifth below this row. Four ca- 
vities belong to the margin of the preoperculum, one 
lying between the latter and the lower jaw, on the 
under surface of which the line is continued by three 
or four depressions, the two front ones, however, being 
small and indistinct. On the eye side the occipital 
branch of the lateral line is of normal structure, and 
extends upwards and forwards, being distinctly visible 
along the base of the dorsal fin to a point almost ver- 
tically above the middle of the upper eye; but there 
are distinct muciferous cavities, though smaller than on 
the blind side, both in the preopercular margin and the 
lower jaw. On the snout too, we generally find three 
cavities in front of the eye, the one nearest to the eye 
being the largest and triangular. At least in one and 
sometimes in two of these last cavities the skin is 
pierced by a small round pore. Between them and the 
lower eye lies the nasal cavity of the eye side with its 
two nostrils, the anterior of an obliquely truncate, tu- 
bular shape, with the truncate (open) side in front, 
and set almost vertically above the front margin of 
the lower eye or a little farther forward, the posterior 
an oblique dermal slit just behind this point, about 
half-way between the anterior nostril and the front of 
the raised and narrow, but obtuse, sharply curved, in- 
terorbital margin of the forehead. The nostrils of the 
blind side are like those of the eye side, but their 
situation is entirely different. On this side the nasal 
cavity lies high up, at the dorsal margin of the head, 
° Goode and Bean (1. c.) mention a specimen 114 mm. long in which the greatest depth of the body was no more than 24 1 of 
the length. The highest proportion given by these writers is 37 '/, %. 
6 In a male from Bohuslan, 411 mm. long, the greatest depth of the body is 30'6 % of the length, in a female 418 mm. long 
32'5 %\ but in another male 378 mm. long the greatest depth is 33'6 °/o of the length. 
c It was these cavities, which are supported in the cranium by upright, thin, osseous bars and ridges, that suggested to Gottsche 
the establishment of the genus Glyptocephalus {yXcrpio, to hollow). 
