LAMELLIBRANCHIATA. 97 



The followins^ figures on PI. lY nia\- serve as illustrations of the above-nieutioued, \'arying 

 form and structiu-e iu Asfar/f horcdlis: 



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

 margin), fairlv light-coloured periostracuni. The shell is rather convex, as is seen from fig. r 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 periostracuni on the lowest part. Western Iceland. 



Figs, id and le represent a strongly compressed form [\i\x. placciitd Morchi with distinct 

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



Fig. if represents a very elongated form [\-2iX.scricea Posselt). East Greenland. 



Distribution. Astnrfe borealis is an arctic and circunipolar sjiecies. In Norway it is said not 

 to live south of Bergen'), 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 Ba}- and thence 

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

 of the North vSea-), 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 bathxinetric distribution is 3 — 26ofm.i|. 



Astarte Montagu! DiUwyn. 

 PI. IV, fig.s. 2 a— c. 



Venus couiprrssa (non Linne) Montagu, Test. Brit. Suppl , 1808, p. 43, PI. 26, fig. i; (Asfarfc) 

 Forbes S: Hanley. Hist. Brit. Moll., I, 1853, p. 464, PI. 30, fig. i; Jeffreys, Brit. Conchol., 

 II, 1863, PI. 37, fig. 3. — I'f/ms Montagui Dillwyn, Descript. Catal. Regent Shells, I, 1817, 

 p. 167. — Nicaiiia Baiiksii Leach, Ross' Voyage of Discovery, 1819, Append, p. 62; »Sars, 

 Moll. Reg. Arct. Norv., 1878, p. 51, PI. 6, fig. i. — Nicania striata Leach, I.e. p. 62. — Astarte 

 globosa M oiler, Inde.x Moll. Groenl., 1842, p. 19; Reeve, Belcher's Last of the Arctic Voy- 

 ages, 1855, p. 398, PI. 33, fig- 6. — Astarte Wartianii Hancock, Ann. Mag. Nat. Hist, vol.18, 

 1846, p. 336, PI. 5, fig. 15—16. — Astarte pulcfiella Jonas, Philippi, Abbild. u. Beschreib. neuer 

 Conchyl., II, 1847, p. 60, PI. i, fig. 12. — Astarte fabula Reeve, I.e. p. 398, PI. 33, fig.5+)- 



Astarte Banksii'hloW^x, Index Moll. Groenl., 1842, p. 19; Morch, Rink's Gronland, 1857, p. 20; Vidensk. 

 Medd. Naturh. Foren. 1S68, p. 223; Arctic Manual, 1875, p. 132; Rink's Dan. Greenland, 1877, 

 p. ,441; Posselt, Medd.om Gronland, XIX, 1895, p. 73, PI. i, fig.s. 1—4; ibid. XXIII, 1898, p. 68; 



') C. G.J oh. Petersen's reference to it as living in Christiania Fjord lOni de skalbierende Molluskers Udbrednings- 

 forhold, 1888, p. 461 is based on a mistake, caused by -■isbjornsen; Brogger has explained (Om "de senglaciale og post- 

 glaciale nivaforandringer i Kristianiafeltet, 1900 -or, p. 581), that Asbjornsen's '\-l.semisukata" was not A.borealis but a form 

 of A- elliptica. 



2) Schrader: Lamellibranchiaten der Nordsee (Inaug.-Dissert.), 1910, p. 43. 



3) As a rule the bouudarv is placed at a depth of ca. 6ofni., but greater depths — down to 260 fni. — are recorded 

 by Friele & Grieg (Norw. Xorth-.\tlantic Exped., MoUusca III, 1901, p. 24) from .Spitzbergen. 



4) For further references to the extensive .synonymy see Kobelt: Prodr. Moll. Test. Mar. Europ., 1S88, p. 395, under 

 Aitnrtc Blinks:! Leach. 



The Ingolf-Expcdition. II. ;. ^3 



