i899-] Tlie History of the European Fauna. 243 



Including Ireland, by the replacement of the Scotch Fir by the Oak 

 really represent some of the stages in the retrocession of the Glacial 

 age. Judging by the luxuriant growth of the Beech in the south of 

 Ireland we have now reached a period, the climate of which is more 

 suitable to that tree than to the Oak. Further there are some theories 

 which base the occurrence of the Glacial period on a variation in the 

 position of the earth's axis, 1 and some account of which might have 

 been expected from Dr. Scharff. If they are to be believed in their 

 entirety, they would surely be highly antagonistic to Dr. Scharff 's views. 



Next, as regards Dr. Scharff 's extensive Glacial European sea, it is 

 the part of a geologist to estimate the exact period in, or the limits to 

 which such a sea must have attained, but there can be no doubt that 

 some such sea is needed to explain the geographical distribution of 

 animals in the Gulf of Bothnia, and the great lakes and inland seas of 

 Asia. How can we explain the presence of a seal (P/ioca sibirica, Sm.) 

 in Lake Baikal, unless there was some direct and fairly easy com- 

 munication thence with the Arctic Ocean ? 



With reference to centres of distribution., Dr. Scharff has a good deal of 

 interest to tell us. We do not feel bound to follow Dr. Haacke's theory 

 of an Arctic origin of life to its utmost limits, but the more we think of 

 the marine faunae of the Pacific and Atlantic Oceans, the more we feel the 

 necessity for an extensive centre for the origin of living things in the 

 Arctic Ocean, perhaps in those flourishing Eocene or Miocene times, 

 when conifers such as Sequoia, Thujopsis, and Salisburia, together with 

 such well-known deciduous trees as beeches, oaks, planes, poplars, 

 limes and magnolias (p. 144), flourished in the congenial climate of 

 Greenland, and when the flora of Spitzbergen and of Alaska was not 

 widely different. Such a centre of distribution is necessary to explain 

 the curious presence of so many closely allied forms in both the N. 

 Atlantic and the N. Pacific, some of them now separated from each other, 

 while others extend the whole way around the arctic shores of Asia and 

 Europe. Thus, to take vertebrates alone, we have the Alcidce and 

 the Phocida, represented in both oceans by species, some of which occur 

 right around the northern coast of Eurasia, while others have separated 

 themselves into two isolated settlements, one confined to each ocean : 

 and the same remark applies to fish. This centre of distribution need 

 in no way interfere with that advocated by Mr. Lydekker, and supported 

 by Dr. Scharff, in the present Oriental region. It was broken up with 

 the advent of the Glacial period, and the^spread of numerous forms from 

 it has given a different complexion to most other regions of the earth. 



Dr. Scharff advocates the existence of several minor centres of origin 

 of life in Europe, such as for the Molluscan genus Clausilia in the south- 

 east (p. 262), and for the slugs of the family Arionida (p. 48) in south- 

 western Europe, perhaps, even in the submerged Atlantis ; but we hardly 

 think that Europe can have ever competed with southern Asia in this 

 respect, at least as regards vertebrates, since the actual area of land 

 available has always been somewhat limited, and the little that has been 

 available has occupied temperate or transitional regions, the Sahara 



1 See a paper by H. Trautschold in the Bull. Soc. Nat. Jl/osc, 1896, No. 2. 



