g LAMELLIBRANCHIATA. 



Jensen, ibid., XXIX, 1909, p. 333. — .ij/r?;-/r j/;-/rt/rt Moller I.e., p. 20; Morch I.e. 1857, p. 20; 

 1875, P- 132; 1877, p. 441. — Astartc pulchella Moreh, I.e. 1857, p. 20; 1875, p. 132; 1877, p. 

 ^\. — Astartc Montagui Morch, Vidensk. Medd. Xaturh. Foren. 1867, p. 95; ibid. 1868, p. 223. 



The "Ingolf" ha.s taken A. Afotitagiii at the following plaees: 



St. 35. Davis vStrait 362 fm. i valve. 



- 33- - ^ 35 - 2 valves. 



- 86. W. of leeland (Brede Bugt) .... 76 - 30 — 



- 87. - - — — — .... no - 2 — 



- 104. N. E. of Iceland 957 - 4 — 



- 113. S. E. of Jan Mayen 1309 - 5 — 



Remarks. In the figures 2 a — c on PI. IV I have compared 3 specimens, which seem to me 

 to illnstrate the main types of this very variable species within the faunistic region dealt with here. 



Fig. 2a represents A. Montagui Dillw. typica. a short and high, somewhat triangular form; 

 the anterior end is a little elongated-rounded, the posterior end shorter, strongly sloping downwards, 

 truncate; the umbones lie a little behind the middle of the shell. 



Fig. 2b represents A. Moniagtti Dillw. var. striata (Leach) Sars, a more elongated form, 

 which stands midway between the foregoing and the following. 



Fig. 2c represents A. Montagui Dillw. var. Warlianii Hancock, the shell of which is elong- 

 ated, elliptical, in general rounded both in front and behind; the umbones lie almost in the middle 

 of the shell. 



The measurements of the three specimens, which I have chosen as types, are as follows: 



Height Breadth 



Length Height Breadth 



Length Length 



A. Montagui typica 14 """. 13 """. 92.9 % 7-5 "'™- 53-6 ° 'o 



— vsiY. striata 15 - '^2> ' 86.7 - 8 - 53.3 - 



— - Warhaini ... 22 - 16.75 " J^-i - 9-5 - 43-2 - 



These three forms are not at all sharply separated, however; all transitions may occur. In 

 discussing the separate geographical regions further opportunity will be taken to mention the variab- 

 ility of this species. 



West Greenland. 



Here the species is common, from the southernmost parts up to Cape York; on the American 

 side it has been taken as far north as 8o°N.L. It occurs most frequently at dej^tlis of 5— 5ofm., but 

 is also met with at greater depths. 



At West Greenland the variety striata is by far the most predominant, and along with it 

 occurs rather frequently the variety glohosa IMoller, which is characterized by an extremely tumid 

 form; the typical form and the variety Warhavii are comparatively rare. At the same time it must 

 be remembered, however, that all possible transitional stages exist between the forms mentioned. 



