1911] PORTLANDIA ARCTICA GRAY 13 



periods of the My tilus-ni veau and Por tlandia-ni veau, 

 and there might be at least, some possibility that the small 

 fragment in question might have been washed out and carried 

 away from such a fossil-bearing terrace. The specimen is 

 characterized by an abruptly cut cauda, and the length of it 

 was measured to be about 37 mm. 



Saxicava pholadis L. var. arctica was found to be 

 characterized by thick shells measuring up to 33 mm. A smal- 

 ler variety, only occurring in somefew specimens, with relatively thin 

 shells, completely resembled the Saxicava arctica L. often found 

 in deposits of the Ra-stage. The number picked up in a short 

 time amounted to thirty. 



The occurrence of this fossil-bearing deposit just between 

 the two main ranges of moraines constituting the double-formed 

 series of the Ra-stage is of great importance as it proves to 

 be the immediate deposition of glacial water during the forma- 

 tion of the second or inner range of the Ra-stage moraines 

 laid down just at the lower end of the Femsjø, a glacial lake 

 about three kilometres farther up in the same picturesque valley 

 of Tistedal. In fact, there is a most direct connection to be 

 found between this fossil-bearing deposit just below the sluices 

 and the large moraine that apparently closes the valley just 

 below the lake of Femsjø. When we leave the fossil-bearing 

 deposit, above mentioned, we may trace the same clay and gravel 

 having been dredged at the upper end of the lock somewhat 

 farther up the valley; in this place, however, we did not succeed 

 in finding any fossils. In some places we find this deposit at 

 the bottom of the valley associated with morainic accumula- 

 tions leading directly up to the large frontal moraine above 

 mentioned. 



Gonsequently, the two ranges of moraines forming the 

 double-formed series are each of them connected with the depo- 

 sits of fluvio-glacial origin laid down at the sea-bottom outside 

 the moraines, and this sea-bottom in both cases, at a con- 

 venient distance from the ice-front, has been crowded with the 

 common mollusca of a true arctic sea. Moreover, we have seen 



