Renews — BeWs Naturalist in Nicaragua. 183 



continent, only the lower lands of the tropics free from the icy 

 covering." (p. 265.) 



The author proceeds to show " that there was much extermination 

 of animal life during the Glacial Period," but " that many species 

 found a refuge on lands now below the ocean that were uncovered 

 b}'' the lowering of the sea, caused by the immense quantity of water 

 locked up in frozen masses on the land." 



" Mr. Alfred Tylor considers that the ice-cap of the Glacial Period 

 was the cause of a great reduction of the level of the sea amounting 

 to at least 600 feet.^ But (Mr. Belt adds) if we admit that the ice- 

 cap existed in both hemispheres at the same time, and extended nearly 

 to the equator, we shall have to speculate on a lowering of the level 

 of the sea to at least a 1000 feet." Strangely enough, in the sentence 

 which follows this heterodox proposition, the author writes — " We 

 have many facts tending to prove that during the extreme extent of 

 the Glacial period the land stood much higher above the sea than it 

 now does." (p. 267.) Surely herein lies the whole explanation of Mr. 

 Belt's difficulties. Islands and isthmuses are but the highest parts of 

 much more extensive tracts of land, which, if elevated by plutonic 

 agency, would (without any reduction of the volume of the sea) lay 

 bare large tracts of land, often of continental extent, and unite island 

 to island, and island to continent, so that the fauna might pass over 

 dryshod, and the flora spread without the agency of man or animals 

 to act as carriers. 



If such explanations (which are deducible from known causes now 

 in operation, and of which instances are actually capable of being- 

 brought forward in evidence) are amply sufficient to meet these 

 zoological and physical geographical problems, why fly to theories 

 which, to say the least, overstrain, if they do not actually violate the 

 known laws of Nature, and override all our first principles both of 

 physics and astronomy ? 



The present day is one of surprises and startling propositions, 

 and it cannot be denied that, in the progress of scientific research 

 and discovery, many of our preconceived and long-cherished notions 

 have been swept clean overboard. It may be that the ideas pro- 

 pounded by the author shall hereafter become a part of the geological 

 principles of a future day ; but will the astronomer and mathemati- 

 cian allow as feasible, under any circumstances, the notion of an 

 ice-cap 8000 feet or more in thickness simultaneously at each pole, 

 and extending thence nearly to the equator over either hemisphere ? 

 We hope not; for the prospect presented to the mind's eye by such a 

 world seems one of the dreariest that man ever pictured, only com- 

 parable in its melancholy lifelessness and annihilation to the vast 

 frozen wastes of Arctic America and Northern Siberia. Even the 

 author would, we think, turn from such a scene of desolation, and 

 wish himself back in the virgin forests of Nicaragua, with its spider- 

 monkeys and humming-birds, and never desire to see ice again as 

 long as he lived ! Mr. Belt's book should be read by all lovers of 

 Natural History, and it is just the kind of book to make Naturalists 

 of those who are not. 



1 Geol. Mag. 1872, Vol. IX. p. 392. 



