FLORA OF THE SHELL-MOUNDS, 179 



to twenty-nine feet ; and as we know that Jutland was 

 anciently an archipelago, and that the Baltic was more open 

 to the German Ocean than it is now, we can easily under- 

 stand that the fluctuations of level may have been greater, 

 and we can thus explain how the waves may have risen over 

 the Kjokkenmodding at Bilidt (which is after all not much 

 more than ten feet aBove the water),, without, resorting to 

 the hypothesis of a subsidence and subsequent elevation of 

 the coast. 



In the Lake-habitations of the Stone age in Switzerland, 

 grains of wheat and barley, and even pieces of bread, or 

 rather biscuit, have been found. It does not, however, ap- 

 pear that the men of the Kjokkenmoddings had any know- 

 ledge of agriculture, no traces of grain of any sort having 

 been hitherto discovered.. The only vegetable remains found 

 in them have been burnt pieces of wood,, and some charred 

 substance, referred by M. Forchhammer to the Zbstera marina, 

 a sea plant which was, perhaps> used in the production of 

 salt. 



The four species which are the most abundant in the shell- 

 mounds are 



The oyster, Ostrea edulis r L. 



The cockle, Cardium edule, L. 



The mussel, Mytilm edulis,. L. and 



The periwinkle, Littorina Uttorea, L. 



all four of which are still used as food for man. Other 

 species occur more rarely, namely,; 



Nassa reticulata r L.. 



Buccinum undatum, L.. 



Venus pullastra, Mont. 



Helix nemoralis, Mull. 



Venus aurea, Gm. 



Trigonella plana, Da. C. 



Littorina obtusata, L. 



