598 



SCIENTIFIC NEWS. 



[Dec. H, 18 



poda known to Britain amount to about one hundred and 

 seventy. Of these about twenty-five are inhabitants of 

 fresh water, the rest being marine, with the exception of a 

 few species whose habitat is almost entirely brackish water. 

 But in addition to these are a considerable number of 

 parasitic and semi-parasitic Copepoda. The former are 

 found attached to fishes, annelids, various Crustacea, 

 and more especially to the compound ascidians, where 

 they subsist on the juices of their amiable hosts, appar- 

 ently causing little, if any, inconvenience to them. Many 

 of the semi-parasitic species appear at times to leave 

 their hosts and wander on their own account through the 

 water, but they are comparatively rare, and usually found 

 in tow-nettings taken after sundown or during the night. 



ANIMAL GEOGRAPHY. 



MOST of our readers have, doubtless, a general 

 acquaintance with the view propounded by Dr. 

 P. L. Sclater, and elaborated by A. R. Wallace in his 

 great work the "Geographical Distribution of Animals." 

 These authorities admit six main regions — the Palae- 

 arctic, the Ethiopian, the Oriental, the Australian, the 

 Nearctic, and the Neotropical — and they base their 

 arrangement mainly on a consideration of the mammalia, 

 endeavouring to harmonise the boundaries thence de- 

 duced with the distribution of other animals. 



Mr. J. A. Allen — not to be confounded with Mr. Grant 

 Allen — proposes eight " realms " — the Arctic, the North 

 Temperate, the American Tropical, the Indo-African 

 Tropical, the South American Tropical, the African Tem- 

 perate, the Australian, and the Antarctic. Other classi- 

 fications, obviously of less merit, we cannot here mention. 



Dr. A. Reichenow, in a recent very elaborate memoir, 

 an abridgment of which appears in Humboldt, recognises 

 in the first place an Arctic " Zone " extending from the 

 north pole southwards to the utmost border of the forests 

 alike in the eastern or western continents. Reichenow's 

 Arctic Zone, therefore, includes the most northern por- 

 tions of the Palsearctic and Nearctic regions of Sclater 

 and Wallace. The whole of America, from the northern 

 boundary of the forests southwards to Cape Horn, is 

 characterised as the Western Zone, and corresponds to 

 the whole of the Neotropical of Sclater and all his Nearctic 

 region south of the forest limit. In justification of this 

 arrangement Reichenow contends that the birds of North 

 America have a decidedly South American character, 

 and have had their " centre of creation or origin " in the 

 latter continent. 



In the eastern hemisphere we find greater complexity. 

 The temperate portion of Europe-Asia extends over 180 

 of longitude, and its southern boundary is more or less 

 closely connected with several parts of the globe situate 

 in the tropics, but distinct from each other. Thus the 

 immigration into the temperate regions has taken place, 

 in his opinion, not from one centre, as in America, but 

 from several. Like Allen, Reichenow concludes that 

 the Malayan (Oriental of Sclater and Wallace) cannot be 

 regarded as of equal value with the former, but must be 

 combined with Africa to form a great territory, the 

 Ethiopian- Malay region, whilst, on the other hand, Mada- 

 gascar has a peculiar and independent fauna. Besides 

 these two regions, we have in the eastern tropics only a 

 third, that of Australia. Immigration into temperate 

 Europe and Asia might have taken place from any of 

 these three faunal territories. But in fact we find that 

 the Eastern Temperate bird fauna has no relation to the 



Australian and the Madagascar fauna, but has a pre- 

 dominating Ethiopian-Malay character. Hence, ornitho- 

 Iogically speaking, Europe and Asia must be combined 

 with the Ethiopian-Malay regions to form the Eastern 

 Zone, comprising accordingly the Palsearctic region ot 

 Sclater and Wallace from the northern limit of the forests, 

 the Ethiopian and the "Oriental regions as far as " Wal- 

 lace's line." This zone is divided into three regions (a 

 " region " in Reichenow's system corresponds to a " sub- 

 region " in that of Sclater and Wallace). The Eastern 

 Temperate region comprises Europe from the above- 

 mentioned tree limit, North Africa to the Senegal and 

 further east to 15 ° north latitude, Arabia except the 

 southern coast, Asia from the tree limit to the Himalaya 

 range and its eastern and western extensions, and the 

 Japanese Islands. 



The Ethiopian region includes Africa from the Senegal 

 and the 15th degree of north latitude southwards, the 

 south coast of Arabia, Socotra, the West African Islands, 

 and St. Helena. 



To the Malay region belong India and South China, 

 the Sunda Islands, including Borneo and Java, Formosa, 

 the Philippines, and the Chagos Islands. 



The Madagascar and Australian faunal territories, 

 though, of course, so far smaller, are considered equal in 

 rank to theWestern and the Eastern Zones, and are charac- 

 terised as the Madagascar and the Southern Zones. The 

 former admits of no subdivision ; it includes, besides 

 Madagascar, the Mascarenes, Comoros, and the Sey- 

 chelles. 



The Southern Zone resolves itselr into two regions ; 

 the one of these, the Australian, includes Australia 

 proper, Tasmania, New Guinea, the Malay Islands to the 

 east of Wallace's line, including Celebes, Lombok, and 

 the Moluccas, and the Polynesian Islands. The New 

 Zealand region comprises, in addition to New Zealand, 

 the Chatham, Auckland, Campbell, and Macquarie 

 groups and Norfolk Island. 



As the sixth and last primary division comes the 

 Antarctic Zone, comprehending the south polar islands. 

 These latter do not, as it might have been expected, show 

 any connection with the nearest continents, but have a 

 striking similarity among themselves. Thus of thirty 

 species of birds which nest in Kerguelen's Land and 

 South Georgia, islands far remote from each other, the 

 half is common to both. The chief islands belonging 

 to the Antarctic Zone are South Georgia, Prince Edward's, 

 Crozet, Kerguelen, Macdonald's Islands, St. Paul's, and 

 North Amsterdam. 



Having thus expounded, without by any means advo- 

 cating, Dr. Reichenow's system, we must point out that it 

 differs less from that of Sclater and Wallace in the 

 boundaries of the respective faunal territories than in the 

 rank which it assigns them. The Australian and Oriental 

 districts retain precisely their former boundaries, but the 

 latter is reduced from the rank of a primary to that of a 

 secondary division. On the contrary, Madagascar rises 

 to the first rank. 



The author, we think, scarcely pays due heed to the 

 palasontological evidence, which is certainly less abun- 

 dant in case of birds than among mammals and reptiles. 

 By going back only, as it appears, to the close of the 

 Glacial epoch, he is enabled to speak of the immigration 

 of tropical forms into temperate Europe and America, 

 and thus to introduce the notion, delusive as it seems to 

 us, of centres of creation or origin, a theory devised in 

 France to weaken, if possible, the evidences of evolution. 



