WMEOLHTESISVOR CAUSE OF AGEACIAL PERTOOS “78s 
land connection. This is most pointedly indicated by the dis- 
tribution of the amphibians of the Carboniferous and Permian 
periods. The Branchiosauria, Aistopoda, Microsauria, and Laby- 
rinthodontia vera were all represented on both continents, and 
unless the doctrine of parallel evolution be pushed to a seeming 
extreme, the only satisfactory explanation is an ample land con- 
nection. The amphibians of today are fatally affected by salt 
water, and even their eggs lose their vitality after a short sub- 
mergence init. It cannot be positively affirmed that this was 
true of the Carboniferous amphibians, but the presumptions 
appear to lie in that line. At any rate the occurrence of all 
the leading branches on both continents renders it quite improb- 
able that a broad ocean intervened. It is therefore assumed 
that the Atlantic Ocean was restricted at the north by such con- 
nection. To be definite, it is assumed that it essentially termi- 
nated south of the Greenland-Iceland-Faroe platform, or possibly 
south of the Telegraphic plateau. 
There are few data that give specific indications as to the 
configuration of the north border of the Pacific at this time, but 
the considerations that have just been urged with reference to 
the distribution of the fauna and flora are apparently best satis- 
fied by supposing an emergence of the very slightly submerged 
continental platform of the arctic region generally. This is in 
harmony with the history of the preceding Paleozoic periods 
during which the Eurasian and North American continents were 
essentially a unit and free migration from one to the other was an 
oft-repeated, if not predominant, phenomenon. If this be the 
true inference the Pacific Ocean was limited at the north to about 
60° eat. 
In equatorial latitudes it is not improbable that the Atlantic 
and Pacific oceans were united between the main bodies of the 
North American and South American continents, so that a com- 
mingling of waters took place here not unlike that which now 
obtains between the Pacific and Indian oceans. 
It is not improbable also, judging from the distribution of 
Permian marine beds, that inland seas extended along the 
