Evolution of Animals 



381 



Group Fresh-water 



genera 



Proteomyxa 16 



Lobosa 14 



Mycetozoa 48 



Heliozoa 15 



Foraminifera terricola 12 



Radiolaria terricola 5 



Foraminifera maricola 



Radiolaria maricola 



Sporozoa 60 



Hsemoflagellata 6 



Mastigophora 94 



Infusoria 95 



Total 365 



394 



has been uniformly accepted for practically all animals. Thus 

 SoUas's highly suggestive paper {128: 87) and Semper's vol- 

 ume equally emphasize this. Sollas says: 



"That the sea is the fertile mother of all life was a poetic 

 fancy which has now become a fair deduction from admitted 

 facts. Indeed, all naturalists are now agreed that all fresh- 

 water animals have descended, directly or indirectly, from 

 marine ancestors; so that the adaption in question must have 

 occurred at some period in the past history of all fresh-water 

 races." And after giving statistical lists of fresh- water and 

 marine forms he proceeds (p. 95): "It will be seen that, as 

 the analysis proceeds, each group furnishes a large number of 

 exclusively fresh-water divisions, while the mixed fresh-water 

 and marine genera, omitting admittedly exceptional cases, 

 are very few indeed." He then advances various weighty 

 evidences in favor of the view that animal life originated in 

 the sea and migrated landward. 



In order to reach a correct conclusion it is necessary that 

 each group should be viewed alike from the phylogenetic, the 

 structural, the taxonomic, and the distributional standpoints. 

 But in the present work only a few observations can be offered. 



