WIIALKS. 209 



been found there, and great glaciers still existing in both. It is expected by some that similar 

 proofs of cold will also be found in the mountains in the south-east of Australia — an anticipation 

 wliich I do not share, because it is nearer the tropics than the limit of glacial cold in the northern 

 hemisphere (except on very high mountains). Any evidences of glacial action in the soutlurn 

 hemisjjhere are no doubt susceptible of the explanation that they may onlj- be of recent phenomena, 

 or that they may have occurred at a different time from, or been alternate with, the glacial cold in 

 the northern hemisphere, but we shall see that such explanations are not reconcilable \\'ith cosmical 

 facts or with the phenomena of the distribution of Whales. 



In the first place, all that we know of the past temperature of the globe, confirmed as that 

 is by the evidences of organic life in the North Polar regions, is opposed to the idea of cold 

 ever having invaded it previous to the glacial epoch ; and as it appeared in the north then, 

 and is present in the same degree, both there and in the south now, the presumption is that it first 

 appeared in both at the same time. 



Previous to the glacial epoch the Dolphin section of Whales had obviously lived in enormous 

 numbers, — at least in the northern hemispliere, — witness the cetolites of the red crag of Suffolk 

 and of the Antwerp beds ; but there is no evidence to show that any of the present Whales 

 then existed. There was one right Whale (B. Lamanoni) whose bones have been foimd in the 

 tertiary beds of Paris, but it was not a polar one, for the heat was greater then than now ; and 

 as the range of large marine animals is even now very extended, it probably was still greater \n 

 the miocene ejioch, when the temperature was more uniform. 



Now the jircsent cold-living Arctic and Antarctic sjiccies must either have been developed 

 out of the miocene species separately in the Arctic and in the Antarctic regions, or they must 

 not. If they were, then, of course, tlie cold must have been present in both hemispheres. If they 

 were not, — and they only first appeared in the polar regions of one hemisphere, — then the species 

 so produced, or their descendants, must have found their way to the polar regions in the other 

 hemisphere across the Equator. But in the present state of things this would be impossible, for, 

 to use Lieutenant Maury's words, " The torrid zone is to the ' Pight Whale ' as a sea of fire, 

 through which he cannot pass." It must, therefore, have been cold enough to allow it to do so, 

 which equally implies that the glacial cold must have extended over both hemispheres. There is, 

 indeed, another alternative, namelj', that out of the Northern Right Whale may have been pro- 

 duced one or more new species fitted for equatoreal life, and that from these again may have been 

 developed in the southern hemisphere fresh species fitted for polar seas. But this is at best but 

 a climisy hj'pothesis ; and it is open to the objection, first, that a reversion to a polar type in a 

 similar form is opposed to the usual working of nature, which never repeats herself; and next, 

 that, in the event supposed, we should still have had the intermediate equatoreal species, of whicli, 

 on the contrary, we have no trace. The inference is to my mind strongly in favour of a general 

 extension of cold having affected both hemispheres ; and I prefer the idea of its having been so 

 great as to have allowed the genus to have passed to and fro from each hemisphere. 



FiNNEKS. (Map 54.) — The Bal.^noptera, Rorquals, or Finners, are the largest of known ani- 

 mals, whether fossil or living. These were separated by Cuvier into three species, the Rorqual of 

 the Cape ; the Rorqual of the Mediterranean ; and the Rorqual of the North. Each of these has 

 now been made the type of a genus. Meg.aptera, the hunchbacked Whales ; Physaltjs, the razor- 

 backed Whales ; and Sibbaldius, wliich latter has again been further subdivided. 



E E 



