Bibliographical Notices. 367 



pie, more akin to the elementary state than those which they 

 have received. By degrees these decompose the organic mat- 

 ters slowly created by plants ; they bring them back little by 

 little towards the state of carbonic acid, water, azote and am- 

 monia, a state which allows them to be returned to the air. 



In burning or destroying these organic matters, animals 

 always produce heat, which radiating from their bodies in 

 space, goes to supply the place of that which vegetables had 

 absorbed. 



Thus all that air gives to plants, plants give up to animals, 

 and animals restore it to the air, — an eternal circle in 

 which life keeps in motion and manifests itself, but in 

 which matter merely changes place. 

 The brute matter of air, organized by slow degrees in 

 plants, comes, then, to perform its part without change in ani- 

 mals, and serves as an instrument for thought ; then van- 

 quished by this effort and broken, as it were, it returns brute 

 matter to the great reservoir whence it came. 



BIBLIOGRAPHICAL NOTICES. 



A List of the Genera of Birds, with their Synonyma, and an Indica- 

 tion of the typical Species of each Genus. By George Robert 

 Gray. Second Edition. 8vo. London, 1841. 



Mr. Gray's ' Genera of Birds ' is a systematic catalogue of all the 

 generic groups which have been proposed by ornithologists, with 

 their synonyms, and a reference under each genus to some one well- 

 ascertained species by way of type. Having on a former occasion 

 (see Annals of Nat. Hist., vol. vi. p. 410, vol. vii. p. 26) jiublished 

 a commentary on this work when it first apjieared, I am induced to 

 offer a few further remarks on this new and improved edition. If 

 the former work was deserving of high praise as a first attempt to 

 introduce order and system into a chaotic mass of scattered observa- 

 tions, this edition may be still further commended on the ground of 

 the great additional accuracy and completeness which it exhibits. 

 In these days of hasty and superficial book-making, it is rare to 

 meet with a work in which so much labour and research is con- 

 densed into so small a space, and as a tabular index of the present 

 state of ornithology, it is one of the most complete works ever pro- 

 duced in any branch of zoology. 



A work of such a nature is well adapted to supply statistical re- 

 sults. The actual number of genera enumerated in it amount to 

 1119. To these genera no less than 1961 Latin or systematic names 

 have been given by diflferent authors, so that 842 superfluous generic 

 names have already been introduced into the science of ornithology. 

 Yes ! it is a humiliating fact, that into this most fascinating portion 

 of Nature's Eden, no less than 842 weeds have been deliberately 

 planted by the hands of those avIio professed to be the cultivators of 



