BY CHARLES HBDLEY. 403 



In the recent fauna there is the same absence of all Mammals, 

 except bats and rats, and the same poverty of Reptiles. Snakes 

 are absent from both, and the Amphibia consist of one in New 

 Zealand and none in New Caledonia. 



Among the moUusca we note in each a close correspondence 

 between Melanopsis, Placostylus, Rhytida, Athoracophoru!^, the 

 Charopa group of Endodonta, and the Rhytidopsis and Monom- 

 phalus groups of Flammulina.''' 



The land mollusca of Lord Howe Island have a close affinity to 

 those of New Caledonia, f 



The foregoing account of the migration and classification of 

 different faunas, usually 'confounded together as Australian, is 

 diagrammatically represented in the accompanying map. 



I beg to point out that this sketch is not constructed from con- 

 tour levels and deep sea soundings. Ocean depths may yield to 

 a zoogeographer valuable suggestions, and such have been here 

 considered, but to follow them implicitly leads straight to error. 

 The fact that older movements may he less and younger more, quite 

 destroys the relevancy between present shallow water and former 

 dry land. In these calculations the sea can be regarded as of 

 one value only, that of a barrier to migration. The difference 

 between a sea fifty fathoms and another five thousand fathoms 

 deep may be that the former is of less duration than the latter. 

 But unless biological data can be educed to support the youth of 

 the smaller depth, it is for the zoologist of equal value to the 

 greater. Thus the Arafura Sea though shallow separates more 

 diverse faunas in Western Australia and Dutch New Guinea 

 than does the deeper water which intervenes between Fiji and 

 the Solomons. 



The land mollusca have served me as a basis in the construction 

 ■of this scheme. 



* Crosse— Journ. de Conch, xlii. 1894, p. 453. 

 t Hedley— Records Aust. Mus. i. 1891, pp. 134-144. 



