TARDIGRADA 181 



described as new species, and 23 could not be identified. Of the 50 named species 

 26 were got in one only of the countries visited ; 14 of these 26 are known in other 

 parts of the world, while 12 are as yet unknown except in the one locality for each 

 here recorded. These last are, of course, among the new species collected by the 

 Expedition. Five of the new species were found in more than one country, or were 

 previously known elsewhere, though they had not been described. 



Australia has most species, viz., 38 (31 identified), Canada comes next with 31 

 (23 identified), New Zealand has 25 (21 identified), the Pacific Islands 18 (15 

 identified), and the Antarctic 5 (4 identified). 



Canada has 7 of the new species, Australia 6 (and 1 new genus), New Zealand 2, 

 the Pacific Islands 1, and the Antarctic 1. 



It is noticeable how much richer the continental areas are than the islands, both 

 in the number of species and the proportion of peculiar species. The isolation of 

 New Zealand, Fiji, and Hawaii does not appear to have led to the development 

 of many new forms. 



As the Tardigrada of Europe are much more fully known than those of any other 

 part of the world, the list of European species may be used as a standard, and it may 

 be instructive to compare the lists of species from the various countries with it, and to 

 note how much they have in common. Canada has 16 species in common with 

 Europe, Australia 17 species, New Zealand 16 species, Pacific Islands 9 species, and 

 Antarctic 3 species. Taking the ratios of these numbers to the totals for each 

 country, it appears that subtropical Australia has in its Tardigrade Fauna nearly 

 as much correspondence with that of Europe as has temperate Canada, where the 

 climatic conditions are so similar to those of northern Europe. New Zealand and the 

 Antarctic have more correspondence than either. For what those figures are worth, 

 New Zealand is most like Europe, the Antarctic comes next, then Canada, Australia, 

 and last of all the Pacific Islands. But there is little to choose between them, and 

 the figures are not worth much, as they would be liable to change whenever further 

 work is done in these countries. 



The peculiarity of the Australian Tardigrade Fauna is greater than we would 

 suppose from a mere consideration of the number of peculiar species. Not only is there 

 a distinct generic type (Oreella), but most of the species (E. pulcher, E. tessellatus, 

 E. interniedius), are conspicuously different from their nearest relatives. Even 

 M. aculeatus, though differing from the African M. crassidens mainly by one external 

 character, is of great interest. The six spines, occupying definite positions as they 

 do on the segments which bear the second, third, and fourth pairs of legs, may 

 possibly be the homologues of the dorsal processes of Echiniscus. If this were 

 the case the occurrence of this species, and of the genus Oreella, would be of 

 great importance in elucidating the affinities of fhe genera Macrobiotus and 

 Echiniscus, 



The existence of these various peculiar forms in Australia serves to indicate that 

 the Australian native Tardigrada are partly at least of very ancient origin, although 



