LamellibranchiaTa. 





The following figures <>n PL IV may serve as illustrations of the above-mentioned, varying 

 form and structure in Astarte borealis: 



Fig. ia represents a specimen without folds and with an almost smooth (fibrous only at the 

 margin), fairly light-coloured periostracum. The shell is rather convex, as is seen from fig. i b. 

 Western Iceland. 



Fig. ic represents a very high form, with quite narrow folds on the uppermost part of the 

 shell and with fairly thick, fibrous periostracum on the lowest part. Western Iceland. 



Figs, id and ie represent a strongly compressed form (wax. placenta Morch) with distinct 

 folds on the uppermost part of the shell. Western Greenland. 



Fig. i f represents a very elongated form (var. sericea Posselt). East Greenland. 



Distribution. Astarte borealis is an arctic and circumpolar species. In Norway it is said not 

 to live south of Bergen 1 ), nor has it been taken living in the Skager Rak or Northern Kattegat; but 

 after this break in its distribution it appears again in the south-western Kattegat and reaches through 

 the Sound and Belts, increasing in numbers but decreasing in size, down into Kiel Bay and thence 

 south of Lolland to a little east of Bornholm (C. G. Job. Petersen). It is said to occur in the middle 

 of the North Sea 2 ), but empty shells only have been found at .Scotland, the Hebrides and Shetland. 

 On the American side the southern boundary lies at New England, in the Pacific at Alaska, the 

 Aleutians and Kamschatka. — Its bathymetric distribution is 3 — 260 fm. *). 



Astarte Montagu i Dillwyn. 



PI. IV, figs. 2 a— c. 



Venus compressa (non Linne) Montagu, Test. Brit. Suppl , 1808, p. 43, PL 26, fig. 1; [Astarte] 

 Forbes & Hanley. Hist. Brit. Moll., I, 1853, p. 464, PL 30, fig. 1; Jeffreys, Brit. Conchol., 

 II, 1863, PL 37, fig. 3. — Venus Montagui Dillwyn, Descript. Catal. Recent Shells, I, 1817, 

 p. 167. — Nicania Banksii Leach, Ross" Voyage of Discovery, 1819, Append, p. 62; Sars, 

 Moll. Reg. Arct. Norv., 1S78, p. 51, PL 6, fig. 1. - Nicania striata Leach, I.e. p. 62. — Astarte 

 globosa Moller, Index Moll. GroenL, 1842, p. 19; Reeve, Belcher's Last of the Arctic Voy- 

 ages, 1855, p. 398, PL 33, fig. 6. — Astarte Warhami Hancock, Ann. Mag. Nat. Hist., vol. 18, 

 1846, p. 336, PL 5, fig. 15— 16. -- Astarte pulchella Jonas, Philippi, Abbild. u. Beschreib. neuer 

 CouchyL, II, 1847, p. 60, PL 1, fig. 12. -- Astarte fahda Reeve, I.e. p. 398, PL 33, fig:- 5 •*). 



Astarte Banksii Moller, Index Moll. GroenL, 1842, p. 19; Morch, Rink's Gronland, [857, p. 20; Vidensk. 

 Medd. Naturh. Foren. 1868, p. 223; Arctic Manual, 1875, p. 132; Rink's Dan. Greenland, [877, 

 p. 441; Posselt, Medd. 0111 Gronland, XIX, 1895, p. 73, PL 1, figs. 1—4; ibid. XXIII, 1898,^68; 



') C. G.Joh. Petersen's reference to it as living in Christiania Fjord (Om de skalbserende Molluskers Udbrednings- 

 forhold, 1888, p. 46) is based on a mistake, caused by Asbjornsen; Brogger lias explained (Oni de senglaciale og 

 glaciale nivaforandringer i Kristianiafeltet, [900-01, p. 581), that Asbjornsen's "A.semisulcata" was not 

 of A. elliptica. 



2 ) Schrader: Laniellibranchiaten der Xordsee (Inaug.-Disserl , [910, p 1.;. 



As a rule the boundary is placed at a depth of ca. 6ofm., but greater depths - down to 2601m. 

 by Friele & Grieg (Norw. North-Atlantic Exped., Mollusca III, [901, p |i from Spil bergeu 



U For further references to the extensive synonymy sec Kobelt: Prodr. Moll. Test. Mar. Europ., iSss. p. 395, undei 

 Astarte Banksii Leach. 



The Ingolf-Expedition. 1 1 , 



