I860.] WOOL — CRETACEOUS PE1UOD. 329 



in the interval between Cretaceous and Eocene times must be now 

 under the Southern Oceans. 



The author then adverted to the circumstance that the recent 

 great wingless Birds and the nearest living affinities of all the 

 Secondary Mammalia yet known occur only in the Southern hemi- 

 sphere. From this, and from some considerations as to the Vegeta- 

 tion, he concluded that, while parts of the Secondary continent yet 

 remain in tbat hemisphere incorporated more or less into the Post- 

 cretaceous continent, other parts of it, such as Australia and New 

 Zealand, have remained isolated up to the present time to an extent 

 sufficient to preclude the migration of Mammalia and wingless Birds, 

 the terrestrial fauna of those lands being the isolated remnant of 

 that of the Triassic or the Oolitic period. He inferred that the 

 wingless Birds, excepting the swift Struthionidae, have been pre- 

 served solely by isolation from the Camivora, which do not appear 

 as an important family tmtil the Pliocene age ; and he instanced the 

 Gastomis of the Eocene (which had affinities with the Solitaire and 

 Notornis) as evidence that the apterous birds had survived until that 

 period, at least when the true Camivora had not appeared. 



An inference was then drawn that the remains of the Secondaiy 

 continent, accumulated to the southward, caused cold currents to 

 flow to the southern shores of the Post-cretaceous continent, causing 

 the extinction of the bottom-feeding and shore-following Tetra- 

 branchiata, to which Mr. Wood attributes the destruction of the 

 Cestracionte which fed on them, and that of the marine Saurians 

 that fed on the Cestracionts. The preservation of the Dibranchiata, 

 on the contrary, was attributed to their being ocean-rangers. The 

 extinction of the Megalosaurians he attributed to the effect produced 

 on vegetation by the alternation of dry seasons during the year, 

 brought about by a great equatorial extent of land, — the extinction 

 of the herbivorous Megalosaurians, by this cause, involving that of 

 the carnivorous. 



The author also alluded to the contiguity of volcanos to the seas 

 or great waters, which he considered t<> admit of explanation by 

 every volcanic elevation causing a corresponding and contiguous 

 depression, which either brings the sea or collects the land-drainage 

 into contiguity with the volcanic region; ami in conclusion ho 

 alluded to the law of natural selection ami correlation of growth 

 lately advanced by .Mr. Darwin, in the soundness ol which he 



asserted his bolief. 



