78 EXPLANATIONS. 



of this kind. Now, in the first place, the affinities 

 of the animal kingdom are only in part made out ; 

 in the second, geological evidence is only partial. 

 We are clearly, therefore, not to expect in nature's 

 museum a full exhibition of any one entire stirps,? 

 as it may be supposed to have passed through its 

 successive stages up to our time. All that we can 

 expect is a succession of fossils marking out por- 

 tions of what we may suppose likely yet to be es- 

 tablished as lines of animal descent. Blanks, and 

 large ones too, must be allowed for; possible; 

 errors as to the animal pedigrees must be con- 

 templated. But, if we have any ground for gene- 

 ralising in a particular direction, as I think there 

 is in this case, we may be held as called upon 

 not to conclude hastily and rashly on the unfa- 

 vourable side, but to look and consider patiently, 

 and to suspend judgment wherever the adverse 

 evidence may appear to be of a nature likely to 

 be reversed. Let us now see how all this applies 

 to the conduct of the Edinburgh reviewer, with 

 regard to the early reptilian fossils. The forma- ; 

 tions where these occur have only been examined? 

 in such a degree, that they are almost every year| 

 giving forth new responses : for example, the ex- 

 istence of birds at this era was not dreamt of ten 





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