424 OKIGIN OF LIFE IN AMEEICA 



of palaeogeography. Professor Benham, moreover, has the 

 advantage of residing in New Zealand, so that his views on 

 these problems are of peculiar interest. To the south of New 

 Zealand, between the latter and the antarctic regions, there 

 are two groups of islands, viz., the Auckland and Macquarie 

 islands. Now it is a specially noteworthy fact, remarks Pro- 

 fessor Benham, that the species of earthworms from Mac- 

 quarie island, and those occurring in the Auckland islands, are 

 more nearly allied to South American and South African 

 species than to those of the mainland of New Zealand. The 

 evidence derived from the distribution of earthworms is, ac- 

 cording to Professor Benham,* strongly in favour of the 

 theory that New Zealand, South America and South Africa 

 were once connected with one another by land. 



A study of the fresh-water crayfishes yields an even more 

 remarkable testimony in support of the same view, at least 

 of the theory that New Zealand and southern South America 

 were connected by land. Dr. Ortmann points out that the 

 family of crayfishes known as Parastacidae is confined to 

 Australia, including Tasmania, New Zealand, southern South 

 America and Madagascar. This family has thus an extremely 

 discontinuous range and must be of great antiquity. Dr. 

 Ortmann f believes that the Parastacidae existed in Australia 

 in Upper Cretaceous times and thence spread by a land con- 

 nection into Antarctica, from which Parastacus reached Chile. 

 Subsequently Parastacus extended its range to Argentina and 

 southern Brazil. Madagascar, he thinks, was not connected 

 with the Antarctic Continent, and received its fresh -water 

 crayfishes by another route. Besides this affinity in the fresh- 

 water crayfishes of the Australian region and temperate South 

 America, there are other crustaceans showing similar features. 

 Mr. Geoffrey Smith J tells us that one of the commonest 

 plankton organisms in the mountain lakes and tarns of 

 Tasmania is the copepod crustacean Boeckella. Now this 

 genus nowhere spreads into the tropics, yet reappears in 

 New Zealand and southern South America. 



* Benham, W. B., " Geographical Distribution of Earthworms," 

 pp. 329335. 



t Ortmann, A. E., " Distribution of Decapods," p. 340. 

 { Smith, Geoffrey, " Naturalist in Tasmania," p. 137. 



