878 EFFECT OF BASSIAN ISTHMUS UPON MARINE FAUNA, 



fathoms. A 35-fathom line on either side would indicate a 

 plateau 80 or 90 miles wide about midway between the shores of 

 the Strait, and on the Victorian side widening out so as to extend 

 up to Cape Howe. The neck of the former isthmus, if the depths 

 remain relatively unchanged, is between AVilson's Promontory 

 and Kent's Group. An elevation of 300 feet would lay dry a 

 tract of comparatively level country between Victoria and Tas- 

 mania rising to a central ridge on the eastern side. 



The proofs advanced by Mr. Howitt are so complete that no 

 opposition is anticipated to the proposition that the Bassian 

 Isthmus existed at a late geologic period. My second proposition 

 that Tasmania at that date stretched farther south is perhaps 

 more in need of support. If the depression of Bass Strait was 

 associated with an undulatory south-north movement, then the 

 Strait would be a trough, Tasmania a crest and the vanished 

 southern tail of Tasmania would fall in a second greater trough. 

 The dissected coast-line and the drowned river valleys of southern 

 Tasmania indicate a recent subsidence. 



Former writers on Antarctica, Dr. H. O. Forbes^ for example, 

 "restored" the Antarctic Continent by filling solid with land the 

 southern quarter of the hemisphere. I have proposed! as a more 

 probable condition, and one that would better suit the distribu- 

 tion of existing animals, that a comparatively narrow tract of 

 land joined Tasmania with Antarctica. This suggestion has 

 received the approval of Dr. A. E. Ortmann,t and for the purpose 

 of the present inquiry may be admitted as a working hypothesis. 



The arrangement of land and water sketched in the accom- 

 panying map and described above would be of later date, say 

 Early Pliocene, than the Antarctic connection. If it at all 

 approximates to the truth, the then condition of what is now the 

 State of Victoria might be compared to the South American 



*Forbes, Supplementary Papers. Vol. iii. Royal Geographical Society, 

 1898. 



+ Hedley, Ann. Mag. Nat. Hist. (6) xvii., Feb. 1896, pp. 113-120. 

 :J: Ortmann, Rep. Princeton Univ. Exped. Patagonia, iv., Pt. 2, 1902, 

 pp. 310-319. 



