Dwellers of the sea and shore dwellersofseasho00crow Year: 1935 48 Dwellers of the Sea and Shore of the salt water. It will be seen, therefore, that the Littorinas are well on the road toward a land life. They are, in fact, gradually substituting lungs for gills. That the Littorinas first acquired the habit of living out of the water through the influence of the tides is not unreasonable to assume. And succeeding centuries gave rise to individuals which were increasingly able to withstand long exposure to the air. But, while this may hold good in the case of this particular group which is es
Dwellers of the sea and shore dwellersofseasho00crow Year: 1935 48 Dwellers of the Sea and Shore of the salt water. It will be seen, therefore, that the Littorinas are well on the road toward a land life. They are, in fact, gradually substituting lungs for gills. That the Littorinas first acquired the habit of living out of the water through the influence of the tides is not unreasonable to assume. And succeeding centuries gave rise to individuals which were increasingly able to withstand long exposure to the air. But, while this may hold good in the case of this particular group which is essentially marine, there would seem to be some difficulty in accounting for those air-breathing littorina; a periwinkles shell. types which undoubtedly had their origin in fresh water. And those types, by the way, have so far pro- gressed that they must have been a long time on the road; in fact, the first to start in the evolutionary pro- cession. But the answer to this is forthcoming. It is pre- sumed that the age of the ocean since the earth assumed its present form is somewhat less than 100,- 000,000 years. Now, as is well known, the sea re- ceives from the land in addition to other elements more than 60,000,000 tons of sodium every year. This sub- stance, dissolved out of the rocks by rains and carried
Size: 1194px × 1675px
Photo credit: © Bookend / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
