6 P. A. øyen [No. ti 



The three above mentioned sand-layers are, however, built 

 up from numerous, very thin layers of different colours, the size 

 of the grams being at the same time very different. The perio- 

 dicity of deposition is very conspicuous. There may be no reason- 

 able doubt that the sand-layers in question really correspond 

 with the complicate moraine ranges forming series of ridges 

 before the lower end or rather in front of the Lake of Maridals- 

 vand. This morainic series proves to have been deposited during 

 climatic conditions of a prominently dichotome character. 



In the present layer, III, we meet with numerous fossil 

 specimens of the following species: — 



Nucula tennis Mont. This species was very numerous, 

 especially in the sand-layers, in places where these layers are 

 built up from fine sand of yellowish-grey colour. A little clay, 

 and gravel may sometimes be mixed with the sand. The species 

 in question belongs to forma typica and often complete speci- 

 mens are found measuring even about twenty millimetres in 

 length. 



Portlandia lenticula Moll. forma typica, of length 6 mm. 

 Complete specimens are often met with. Juvenile specimens are 

 of a rather ovate shape. 



Area glacialis Gray. This species proves, in this series, 

 to belong to a rather small variety of length 10 mm. or in some 

 individual cases somewhat more. This variety, moreover, proves 

 to belong to var. raridentata Wood (Forbes & Hanley: History 

 of British Mollusca, Vol. II, 1850, pp. 241—243, Pl. 45, fig. 8). 

 In the specimen pictured by Forbes and Hanley the index is 

 0,708. But, in the series in question at Bentse, however, even 

 one specimen was measured to be of length 9,5 mm. and height 

 7,0 mm. rendering an index of no less than 0,737. 



Axinus sp. was not rare but only occurred in a rather 

 small species, the individual specimens of which seem to some- 

 what differ in shape between that of v. flexuosus and v. gouldii. 

 It ought, however, to be referred to A. flexuosus Mont. 



