KUNGL, SV. VET. AKADEMIENS HANDLTNßAH. BAND 48. N:ü 1. 



61 



elevated shells of coarse sculpture occur at Hackluyts Headland and in Stor Fiord, 

 at the first named locality mixed with transitions to var. 2 a. 



Greenland, h. 



4—5 



6-7 



9—10 



13—14 



max. 18.5 (64° 56' N.) 



limits of variation; ap. 



2.,5— 3.G 



3—5.3 



4.2—6.8 



6.3 — 8.7 



10.5 



130 sps measured d. 



5—6 



6.4—10,8 



0.3 — 14 



13—18.5 



24 



wh. 



4V'-5 



5-6V-' 



Ö'A— 6 



6— 6V2 



7 



Two extreme forms may be distinguished, forma typica and var. umbilicalis, 

 which are connected by series of intermediate forms. Forma typica is more elevated, 

 usually sculptured in accordance with a) or b) (see above), though coarsely sculptur- 

 ed forms, similar to the Norwegian shells, are more rare. Var. umbilicalis is usually 

 smooth or feebly sculptured ; in young specimens, as also in the upper whorls of the 

 older ones, a coarser sculpture always appears. Specimens of var. umbilicalis from 

 East Greenland, described by Hägg, 1905, are strongly sculptured. Form and sculpture 

 are not in reciprocal relation to each other, though in high shells the sculpture is 

 usually more distinct, in lower ones more feeble, yet all combinations of form and 

 sculpture occur. 



Newjoundland. These shells are similar to the Norwegian form, but are com- 

 paratively more depressed; they also resemble specimens from Greenland. 



Variation of the radula : The number of median teeth is constantly 6 on each 

 side and an incomplete lateral tooth always occurs outside of them. This number is 

 present even in very young specimens (cfr PI. 6 fig. 20). The number of lamellae 

 varies between 70 (fig. 16, Julianehaab) and about 100 (fig. 17, Berufjord), the average 

 being about 90. In young specimens a lesser number occur e. g. 50 (fig. 20). The 

 rhachian tooth may be of a more quadrangular shape, more or less dilated, but these 

 characters pass over into one another, and no rules for correspondence with the 

 shell characters are possible of establishment. Var. umbilicalis varies in this respect 

 similarly to forma typica. 



(general Distribution: 



Norway: arctic region (h. 15; d. 14; G. 0. Sars 1878; Schneider 1881, 1885, 

 1891, 1894; Aurivillius 1886; Bidenkap 1897; Norman 1902); west coast (Friele 1874; 

 Lilljeborg 1851; Metzger 1875, 0-20 fms; Nordgaard 1907); Norwegian Sea (Friele 

 1901). - British Islands (Jeffreys 1865); North Channel (Jeffreys 1883). — Between 

 Shetland and Faroe Isles, 93—150 m (Simpson 1910). — Faroes, 650 fms (Mörch 

 1868; Jeffreys 1883). - Iceland (Mörch 1869'; Verkrüzen 1872; Johansen 1902). - 

 Jan Mayen, 30 fms (Friele 1878). — Murman Coast, White Sea, Nova Zembla ; Kara 

 Sea (Herzenstein 1893, Dautzenberg 1911). — Russian Lapland ( Middendorf f 1849). — 

 Barent Sea, 25 fms (D'Urban 1880); D:o, 150-170 m ( + var. umhilicalis, 66-194 m ; Kni- 

 powitsch 190P). — Kara Sea, 5-60 fms (Leche 1878; Collin 1887). — Franz-Josef Land, 

 26— 110 m (Knipowitsch 1901''; Melvill & Standen 1900). — Spitzbergen, to 98 m (Km- 



