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NATURE 



\yune 29, 1876 



and of the Neotropical regions, no one surely could 

 have been more competent than Mr. Wallace to select the 

 most characteristic forms for these plates, and we have 

 great pleasure in reproducing some of them in these 

 columns. 



To those who know anything of Natural History the 

 enormous labour involved in the compilation of these six 

 memoirs will be at once apparent. The mass of details 

 to be gone through in bringing together the most pro- 

 minent known facts connected with the m9.mmals, birds, 

 reptiles, amphibians, fishes, butterflies, beetles, and 

 land-shells of every different part of the world's surface, 

 is a task that the boldest naturalist might well stand 

 aghast at, especially when it is recollected that these de- 

 tails have to be picked out from several hundred different 

 works and periodicals published in every quarter of the 



globe. That errors can be escaped in such a compilation 

 even by a writer so cautious and so competent as Mr. 

 \yallace is manifestly impossible. No intellect could ex- 

 pect to obtain personal acquaintance with more than a 

 {^"^ selected branches of such a multifarious subject, and 

 for the rest an author must trust to second-hand infor- 

 mation. The selection of such second-hand information 

 and its reduction into a uniform shape, is of itself a task 

 of appalling magnitude, and we can only congratulate 

 Mr. Wallace on having had strength and leisure to 

 accomplish such a Herculean labour. 



The fourth and last part of Mr. Wallace's work con- 

 tains, as we have already explained, a review of the dis- 

 tribution of the different groups of animals which he has 

 selected for the illustration of geographical distribution 

 arranged in systematic order. The families are taken up 



Fig. 4. — A Forest Scene_on the Upper Amazon, with some Characteristic Birds. 



one after another, the principal genera are mentioned, 

 and notes are given on the more remarkable species. At 

 the end of each order is appended a series of remarks on 

 the general distribution of the whole group. This is in 

 fact the storehouse of information from which the essays 

 on the six zoological regions have been compiled, and 

 should in strictness have preceded the third section 

 of the work instead of following it. The author wisely 

 recommends persons not well versed in zoology to 

 read the more important parts of it — especially the ob- 

 servations at the close of each order — before they begin 

 Part III. As regards this systematic treatise the obser- 

 vations which we have already made on the difficul- 

 ties to be mastered in the compilation of the memoirs 

 relating to the six geographical regions are still more 



applicable. It would be easy to point out many pas- 

 sages in which Mr. Wallace has not in our opinion 

 made the most judicious choice of authorities. Errors of 

 detail are, however, as has been already stated, unavoid- 

 able in a work of this extent — happy is he who makes 

 fewest of them ! Even in the case of some of the largest 

 and most prominent families of the great class of 

 mammals, naturalists are by no means yet agreed as 

 to the number of species and genera that should be 

 admitted. For example, Mr. Wallace, we observe, 

 assigns "four, or perhaps five" rhinoceroses to Africa, 

 but Prof. Flower — one of the highest living authorities on 

 this class of animals, in a recent paper read before the 

 Zoological Society of London — could only recognise two. 

 Mr. Wallace admits the validity of Elasmog;nathus of 



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