Waltker — Origin and Peopling of the Deep Sea. Gl 



North Europe. All this points to the conclusion that during 

 these long periods an Atlantic land connection existed hetween 

 both continents which to-day is in part deep sea bottom. 

 Similar facts force the acceptance of the opinion that the 

 present Indian ocean throughout long periods possessed a land 

 bridge from Africa to India and Australia. Finally, how can 

 we explain the occurrence of entire skeletons of hippopotamus 

 and African elephants in very ancient bone caverns at Palermo 

 except by the conclusion that Sicily was once joined with 

 Africa, although now a deep sea exists between the two shores ? 

 For a passive transportation of these gigantic animals is not to 

 be considered. 



Aside from a few local exceptions where deep sea bottom 

 has again become land, there are numerous cases in all parts 

 of the earth where we can show that great portions of the 

 firm earth crust through sinking have become changed into 

 sea bottom. In other words, the deep sea has grown at the 

 expense of the shallow sea and the mainland. 



The great interest of geologists in the investigation of the 

 deep sea arose when the elder Sars discovered in the Lofotens 

 at a depth of 1000 meters a small sea lily, Rhizocrinus lofo- 

 tensis. The stalked sea lilies up to this time had been held as 

 an entirely extinct group which in the geologic past had pos- 

 sessed a great significance, inhabiting the former seas in hun- 

 dreds of genera now extinct. Out of the deep sea there was 

 then drawn such an ancient animal still living and at once then 

 arose the hope of obtaining by methodical dredging of the 

 deep sea bottom other animal species also believed to be 

 extinct. It was one of the more important tasks of the Chal- 

 lenger expedition to seek after these very ancient types. 



A number of expeditions have now explored the bottom of 

 the deep sea and we know very well the systematic interrela- 

 tion of the present deep sea fauna and its characteristics 

 acquired by adaptation to the peculiar environmental condi- 

 tions ; and it seems a praiseworthy task to prove the geologic 

 age of this fauna, just as paleontologists do in determining 

 the age of an extinct fauna. It is well known that in each 

 period of the earth's history different sea animals have lived ; 

 let us now compare the present deep sea fauna with the chron- 

 ologically arranged' faunas of the past. ' 



To this end we must first point out that not a single animal 

 characteristic of the Paleozoic is found in the present deep sea. 

 The Archseocyathidae, Tetracoralla, Tabulata, Stromatopora, 

 Spiriferidse, Graptolithidse, Cystidea, Blastoidea, Paleocrinoi- 

 dea, Orthoceratidae, and Trilobitte are completely lacking. We 

 might then perhaps surmise that in general no Paleozoic forms 



