in)LE-FLor.\l)El{. 



379 



98; ibid. 1879, No. 1, p. 82; Norsk Nordh. Exp., ZooL, 

 Fiske, p. 150; Malm (^Pleuronectes), Gbi/s, ISoli. /'n.,p. 527; 

 WiNTH., Naturh. Tidskr. Kbhvn, ser. 3, vol. Xll, p. 40; 

 GooDE, Bean {Glyptocephalas), Proc. U. S. Nat. Mus. vol. 1 

 (1878) p. 19; H.\NSso.N, Ofvers. Vet.-Akad. Forli. 1880, 

 No. 4, p. 52; Mon. (Platessa), Hist. Nat. Foiss. Fr., torn. 

 Ill, p. 29G; JoRD., GiLB. (Gh/ptocephalus), Bull. U. S. Nat. 

 Mus., No. 10, p. 838; Day {Pkuronectes), Fish. Gt. Brit., 

 Irel., vol. II, p. 30, tab. GUI; MdB., Hcke, Fiscli. Osts., 

 p. 99; LiLLj., Sv., Norg. Fn., Fisk., vol. II, p. 38('.; Gthh, 

 Voy. Chall., Deep-sea Fish., p. 166. 



Pleuronectes Saxicola, Faber, Tidskr. f. Natuiv., Bd. 5 (1828), 

 p. 244; Isis 1828, p. 877; Gottsche (Glyjitoccphaliis), 

 Wiegm. Arch. Naturg., Bd. I, part. 2, p. 156; Kit. (Ptatessa), 

 Damn. Fiske, vol. 2, p. 338. 



Pleuronectes nigromamts, NiLSs., Prodr. Ichth. Scand., p. 55; 

 Schagerste., Physiogr. Sallsk. Tidskr., Heft. 2, p. 312; 

 Valejjc. apud. Gaim, Voy. Isl., Groenh, J'oiss., tab. 13. 



Platessa pola, Jicnyns, 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. Conip. ZooL, Harv. Coll., vol. XV, p. 24. 



Platessa elongata, Yarr, 1. c, p. 318; Gthr {Pleuronectes), 

 1. c, p. 450; Day, Proc. Zool. Soc. Lond. 1879, p. 755, 

 tab. LXI; Gill {Glyptocephabis), Proc. Acad. Nat. Sc. Philad. 

 1873, p. 362. 



Glyptocephabis acadianus, Gill, 1. c. (vide Goodk et Bean, 

 1. c). 



The elongated (narrow elliptical) and thin shape 

 of the body, the large nnniber of rays in the dorsal 

 and anal tins, the cavities in the head (especially on 

 the blind side), and the black colour of the outer half 

 of the pectoral tin 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 {Ji/de- 

 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 '/g of the length of the body, but sometimes" 

 sinks as low as V4 thereof. The males of this species 

 are probably, as a rule, no more elongated than the 

 females'. Behind the head the body grows thinner 

 and thinner posteriorly. Tlie Danish fishermen, accord- 

 ing to Gottsche, call this species on account of its 

 transparency Spin(JelJfi/nder=Sin(\er (Cobweb) Flounder. 

 The greatest thickness of the head, straight across the 



upper articulation of the preoperculum, measures only 

 about ^/g 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 cernita, 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 tlic in-eopercular margin and the 

 lower jaw. ( hi the snout too, we generally find three 

 cavities in front of the eye, the one nearest to the eye 

 being' the largest and trianoular. 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 loAver 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' ., of 

 the length. The highest proportion given by these writers is 37'/, %. 



* In a male from Bohuslan, 411 ram. long, the greatest depth of the body is 30'6 °o of the length, in a femah' 418 umi. long 

 32'5 %; but in another male 378 mm. long the greatest depth is 33-6 "« of the length. 



•" 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 Glyptocephabis (yXirfOJ. to holloir). 



