Fauna and Flora of New Zealand. 81 



none of which are known in Tasmania. Of these perching 

 birds, Z. cosrulescens first appeared in New Zealand about 

 thirty years ago; H. nigricans, A. carunculata, E. pacificus, 

 and G. parvirostris are occasional stragglers, not naturalized ; 

 while C. plagosus migrates annually to and from Australia. 

 There are also two freshwater fishes, both of which go to the 

 sea to breed, common to Tasmania and New Zealand. No 

 freshwater shells and no land-shells, with one doubtful excep- 

 tion *, are known to inhabit both places ; no sphinx moths 

 and but very few insects of any kind, some of which may 

 have been introduced. If we were to include allied species, 

 the list of plants would be increased, but not very much. On 

 the other hand, some of the plants, birds, and insects may 

 have migrated into both Tasmania and New Zealand from 

 the north, and may never have crossed the intervening ocean ; 

 while some of the birds and insects may have been helped 

 across by ships, and are not therefore fair examples of natural 

 dispersal. On the whole we may well be astonished that, 

 notwithstanding the strong westerly cyclones and the special 

 facilities afforded by petrels, no animals except a few birds 

 and insects and but few flowering plants have been able to cross 

 this very ancient barrier of from GOO to 900 miles of ocean. 

 This is the more remarkable when we remember that the 

 floras of Kerguelen's Land, the Orozets, and Marion Islands 

 are almost identical, although the islands are more widely 

 separated than New Zealand is from Tasmania, and they are 

 of much smaller dimensions. The conclusion is that this 

 antarctic group of islands must either have been connected or 

 else separated by channels much less than 600 miles across at 

 some former period. 



I have already said that the greater part of the north-tem- 

 perate plants spread over the southern hemisphere with the 

 antarctic plants ; and there can be no doubt that they 

 migrated from the north to the south along the great meridi- 

 onal chains of mountains in a "continuous current of vegeta- 

 tion," as first shown by Sir J. Hooker, and subsequently 

 advocated by Sir C. Lyell, Darwin, and Wallace, But I 

 think that too much stress has been laid on the necessity for 

 a series of alternating glacial epochs in each hemisphere to 

 enable the plants to pass over the equatorial regions. Mr. 



* Paryphanta MUiiymii.—A large species with a wide aperture, living 

 in damp woods, and not at all likely to stand a voyage. JSew Zeahu d 

 and Tasmanian specimens have not been compared, and the dentition of 

 both is unknown. In New Zealand the species has been found in one 

 localitv onlv. 



