LAMELLIBRANCttlA^A. 89 



Both Morcli and Posselt lia\c noticed tliat the species is variable. The former remarks: 

 "The Icelandic specimens are nnich more thick shelled and elongated than those from Cireenland". 

 Posselt modifies the last part of the sentence in the following statement: "Tlie variety nhlonga, 

 which is the commonest form at Iceland, is met with here and there at South Greenland". So far as 

 I can judge, there is no such connection between the geographical distribution and the outer form 

 of the animal; the variation seems rather mdividual. In any case, Morch's statement is erroneous in 

 regard to the first point and greatly exaggerated as to the second. 



In PI. Ill, fig. 12 a I have represented a small specimen of the strongly scul])tured, youthful 

 form, which might possibly give rise to difficult}- in the determination, if it occurred isolated. Further, 

 for the sake of comparison I give a comparatively smooth specimen (PI. Ill, fig. 12b), on which, however, 

 as usual the prodissoconch is strongly sculptured. 



Isocardiidae. 



[Isocardia cor Linne.] 



Posselt has introduced this characteristic Bivalve into the fauna of Greenland. In the vStock- 

 holm Museum he found, namely, a fragmentar>- valve, 70 " "'. long, taken according to the label by 

 the Swedish Exped. of 1871 at 63°35'N. L., 52°57'W.L. and a depth of 43 fm. "To judge from the 

 discovery of the dead valve, it ma}' be taken as probable, that Isocardia cor lives in the Davis Strait", 

 writes Posselt •). 



W. C. Brogger ^), on the other hand, has pointed out, that Isocardia cor, which is a southern 

 (Lusitanian) form, at the present time to be considered a great rarity on the Norwegian coasts, is 

 certainly extinct at Greenland, and that the fragment mentioned by Posselt must in all probability 

 have belonged to a fossil specimen. 



As I.cor does not occur at the Faeroes, nor at Iceland, which have a much milder marine 

 climate than West Greenland, and as it does not occur at North America either, I also think it quite 

 improbable that it lives on the banks in the Davis Strait. 



During a visit to the Stockholm Museum I came to the conviction, that an exchange of label 

 had probably taken place, and that the valve referred to had not been taken at Greenland at all. In 

 any case Isocardia cor should be struck out of the Greenland fauna. 



Cyprinidae. 



Cyprina islandica Linne. 

 Venus islandica Linne, Syst Nat. ed. 12, i, 2, 1767, p. 1131. — Cyprina islandica Jeffreys, Brit. 



Conchol. II, 1863, p. 304, PI. 36, fig. 2; Gould & Binney, Rep. In v. Mass., 1870, p. 129, fig. 443. 

 Cyprina islandica Morch, Rink's Gronland, 1857, j). 92; Vidensk. Medd. Naturh. Foren., 1867, p. 94; 



ibid. 1868, p. 221; Arctic Manual, 1875, p. 132; Rink's Dan. Greenland, 1877, p. 441; Posselt, 



Medd. om Gronland, XXIII, 1898, p. 61. 



1) Medd. om Gronland, XXIII, 1898, p. 54. 



2) Brogger: Om de senglaciale og postglaciale nivaforandringer i Kristianiafeltet, igoo -01, p. 591. 



The Ingolf-Expediiion. II. 5. 12 



