REVIEWS — NATURAL HISTORY. 245 



and sub-genera have been established. For the present their sub-division must be 

 left to arbitrary estimations, and we shall have to deal Avith them as well as we 

 can, as long as the principles which regulate these degrees in the different kinds 

 of.groups are not ascertained. I hope, nevertheless, that such arbitrary estima- 

 tions are for ever removed from our science, as far as the categories themselves 

 are concerned." 



We are quite prepared to go vs^ith our author to the extent that, in 

 every really good classification, man is only the interpreter of nature, 

 and that every division rests upon really natural characters ; but vre 

 must confess to some doubt as to the possibility of laying down pre- 

 cise laws as to the kind of characters upon which each degree in classi- 

 fication must be founded, and we must add that when we test the 

 accuracy of the learned author's views, by the consideration of his 

 own system, we cannot resist the conclusion that there is still some^ 

 thing wrong, either in his principles or in their application. We are 

 not easily convinced, for example, that fishes demand four classes in 

 order properly to express their relations. Embryology is destined to 

 afford tlte most important assistance to the naturalist, but the real 

 value of its revelations must be judged of by comparison vdth other 

 well established principles, and we must not be hastily led by it to mul- 

 tiply leading divisions. We are bound to acknowledge that our author 

 proposes these classes with great modesty, and vdth some hesitation ; and 

 whilst expressing a present strong feeling against them, we would be 

 prepared candidly to consider any evidence that may be produced. 



The account given of various systems of classification is very valuable, 

 and shows the author's power of doing justice to those whose views 

 differ vndely from his ovm, and appreciating what is good whilst 

 offering candid criticism. Possibly Macleay and his followers have 

 found in him the least appreciation of the kind of merit they possess, 

 and may justly seem to be undervalued ; but this part of the work 

 will be found useful by many, and its execution cannot but be admired 

 for extent of information, clearness and conciseness of statement, 

 and liberal though profound criticism. 



It is time now that we invite the reader's attention to the first mon- 

 ograph, a treatise on North American Testudinata. Any attempt, 

 within the space we can command, to give an abstract of the contents 

 would be useless, and still less can we give expression to the doubts or 

 difiiculties which occur to us. The author makes Testudinata (a name 

 which has precedence of Chelonians) the highest order of the class 

 Reptilia, and considers it as containing the two sub-orders Chelonii 

 and Amydae, the former of which he makes to consist of two families 



