XII JAPANESE SUB-REGION — AUSTRALIAN REGION 369 



author, from an examination of the shells dredged by Mac- 

 Andrew at Suez, regarded 17 species as common, and Mr. E. A. 

 Smith has confirmed this view with regard to 8 of the species in 

 question.^ The Mollusca occurring in Post-pliocene beds at Suez 

 show that Mediterranean species lived there in comparatively 

 recent geological times. 



The opening of the Suez Canal appears to have already 

 induced several species to start on their travels from the Medi- 

 terranean to the Red Sea and vice versa. Two Red Sea species 

 (^Mactra olorina Phil., Mf/tUus variabilis Kr.) had in 1882 estab- 

 lished themselves at Port Said, while two Mediterranean species 

 (^PJiolas dactylus L., Solen vagina L.) had reached Ismailia.^ 



(2) The Jaj)anese Sub-region consists of the Japanese Islands 

 to Niphon, together with Corea and a stretch of adjacent main- 

 land coast of unknown extent. The warm Kuro Si wo current, 

 sweeping up between Luzon and Formosa, permits tropical species 

 to extend much farther north than on the opposite shores of 

 America, where a cold polar current keeps them back. A certain 

 number of species, however, are common to the two shores of the 

 Pacific, and a few circ unipolar species occurring on our own 

 coasts reach Japan, e.g. Troplion clathratus., Puncturella noachina, 

 Mya arenaria.^ Modiola modiolus^ Lasaea rubra, and Nucida tenuis. 



Among the characteristic genera are Fasus, Siphonalia^ Colum- 

 barium, Hemifusus., Rapana., CJdorostoma., Pleurotomaria., Hali- 

 otis, and Cyclina. 



C. The Australian Region 



includes the Australian coast-line from about Swan R.^ (lat. 

 32° S.) to Sandy Cape (lat. 25° S.), Tasmania, New Zealand, and 

 the adjacent islands (except Lord Howe's L). 



(1) The Australian Suh-region proper (which consists of the 



1 A. H. Cook, Ann. Mwj. Xat. Hist. (5) xviii. (1886) p. 380 f ; E. A. Smith, 

 P. Z. S. 1891, p. 391 f. 



2 C. Keller, Neue denksch. Schw. Gesell. xxviii. 1883, pt. 3. 



3 According to Tate ( Trans. Boy. Soc. S. Austr. 1887-88, p. 70), ' Australian ' 

 species predominate at Freemantle (32'^'), but Tenison-Woods (J. Boy. Soc. iV. 

 S. Wales, xxii. p. 106) holds that the tropical fauna extends as far south as Cape 

 Leeuwin (34°), and that the Australian forms are not predominant until the 

 extreme south. Tenison-Woods regards Cape Byron (31°) as the limit of the 

 tropical fauna on the east coast, while some characteristic tropical genera reach 

 Port Jackson, and a few (e.g. Cypraea annulus) Tasmania. 



VOL. in 2B 



