‘Later periods of the Glacial Formation. 29 
have not been carried to their present position is obvious, 
from the frequency of the littoral Balanus, still entire, adher- 
ing to the shells and stones, and even to the rock itself. 
Further, the shells found in these masses are, without ex- 
ception, of littoral (for the most part) or laminarian species, 
the latter, as is the case on existing sea-beaches, having 
been washed up from the lower zone. Not one deep-water 
species has ever yet been found in these shell-beds. 
The arctic character of these beds is still further confirmed 
afresh by the specific nature, the numerical proportions,* and 
the actual size and shape of the shells which form them. 
The elevation of the land seems to have taken place gradu- 
ally and without violence, accompanied by a corresponding 
diminution in the arctic character of the fauna. 
2. The older clay containing shells rarely aggregated in 
any number, generally sporadically dispersed or thinly spread, 
usually entire and well preserved, and the bivalves in pairs. 
This is plainly a deep-water formation, the shells and 
Echinoderms found in it belonging to the deep-sea zone. 
Dentalium abyssorum, Yoldia pygmea, Y. lucida, Arca gla- 
cialis, &c., are frequent. Srphonodentalium vitreum, Iso- 
cardia cor, &c., are rarer. Serpula polita is frequently found 
attached to the erratic blocks which abound in this clay. 
The fauna of this clay is markedly arctic. Thus Arca 
glacialis lives now only in Finmark, Spitzbergen, and Mel- 
ville Island: Yoldia intermedia, discovered by Dr Sars in 
Finmark at 100 fathoms deep, and Siphonodentalium vitreum, 
a rare Finmark species, living from 40 to 100 fathoms deep, 
and apparently approaching extinction, are much more fre- 
quent in the clay-beds. 
The evidence of the Echinoderms supports that hitherto 
obtained from molluscs alone. Ophiwra Sarsit lives along the 
whole coast of Norway, at from 20 to100 fathoms andupwards, 
but is more frequent and larger in the far north. Ctenodiscus 
erispatus, distinctively arctic, comes south to Christiansund, 
Lat. 63°10, at from 40 to 200 fathoms. Tripylus fragilis, 
peculiar to Norway, is larger and more frequent in the north, 
but comes south to Bergen at from 30 to 120 fathoms. 
* Thus Saxicava rugosa, Mya truncata, and Pecten islandicus, form from 50 to 
80 per cent. of the whole shells. 
