296 



As every possibility of mistake seemed to be out of the 

 question 1 no longer concealed for Dr. Engell that the valves 

 he had found originated from Zirphaea crispata and that the 

 occurrence of this bivalve proved the layer to be deposited 

 during more genial cUmatic conditions than we find at Green- 

 land at present. 



The one is a right valve, the other a left of a length of 

 respectively 48 and 65 mm.; they are without periostracum and 

 bleached, but otherwise well preserved; one shows holes made by 

 the polychaetous Annelid : Pohjdora ciliata Johnst. On the valves 

 was left a little of the surrounding soil consisting of coarse sand 

 whose mineralogical composition, after an examination by Mr. 0. 

 B. Böggild, fully agrees with the material from the mussel-layer. 



That Zirphaea (Pholas) crispata L. no longer lives at 

 Greenland may be regarded as a fact. Surely we do not often 

 get living specimens of this burrowing bivalve in the dredge; 

 more frequently we dredge its dead valves or find these washed 

 ashore. But in no respect the least trace of Zirphaea crispata 

 is at hand from Greenland. 



The American authors agree that the northern limit of 

 the present distribution of this bivalve is in the eastern Canada 

 at Gulf of St. Lawrence (Rimouski) ^). Its proper home is at 

 New-England. The southern limit cannot be fixed. 



On the European side of the Atlantic it is distributed from 

 the western France to the northern Norway, where it has 

 been found in a few localities in the West-Finmark, but not 

 in the East-Finmark *). It lives moreover at the south-western 

 Iceland where it was observed by Eggert Olafsen ^). 



^) Venill <fe Smith: Report upon the hivertebiate Animals of Vineyard 

 Sound and adjacent waters, 1894, p. 377; J.W.Dawson: The Canadian 

 Ice Age, 1894, p. 227; Whiteaves: Catalogue of the Marine Inverte- 

 brata of Eastern Canada, 1901, p. 151. 



^) G. 0. Sars: Mollusca Regionis Arcticae Norvegiae, 1878, p. 97. 



=•) Olafsen: Reise igjennem Island, 2. Ü., 1772, p. \00d {Pholas ... truncaia. 

 Tab. XI, Fig. 3, 4 & 6). 



