1913] TRANS1TI0NAL QUATERNARY STRATA 9 



tion forms a well developped and rather prominent terrace at 

 an altitude of nearly eighty tvvo metres above the level of the 

 sea. And, a terrace of about this height has, indeed, in other 

 parts of the Valley of Aker been recognized as forming part of 

 the Pholas- nivenu. In the present section, VI, of the deposit 

 at Bentse the very same fact is strongly indicated by the rich 

 occurrence of a rather large type of Mytilus edulis Lin. in the 

 upper part of this section. The mode of occurrence of this fossil 

 species as well as the tough constitution of the soft and fine 

 clay make this terrace so much resemble the Pholas-deposh, for 

 instance near Solberg, that there can be no resonable doubt as 

 to their common origin. On the other hand, the fossil assemblage 

 of faunistic remains of section VI at Bentse proves that the 

 lower part of this deposit has been laid down during an earlier 

 geological stage, viz. that of the Littorina - n i v e a u . The fol- 

 lowing species were found : — 



Mytilus edulis Lin. forma typica in specimens measuring 

 about sixty millimetres in length. This species was rather nu- 

 merous. 



Portlandia lenticula Moll. forma typica of length 5 mm. 

 Juvenile specimens are of a more ovate shape. 



Area sp. A small fragment possibly belonging to some one 

 of those species was found in the lo west part of this section. 



Macoma calcaria Ghemn. vas rarely found as occurring in 

 a small type with thin shells, being somewhat similar to var. 

 sabulosa in its outer shape. 



Macoma baltica Lin. was rather numerous, but as a rule 

 only occurred in rather small specimens with relativeiy thin 

 shells. Juvenile specimens sometimes make one be reminded 

 of v. calcaria or v. torelli. Quite exceptionally juvenile speci- 

 mens are met with having the frontal trunk somewhat elongated 

 at the same time as the caudal one is rather shortened or even 

 stunted so as to make one be reminded of v. lovéni; the author, 

 on a former occasion ("Skjælbanke-studier i Kristiania omegn", 

 1907, p. 37) described, a similar type as occurring in the 



