490 Recenthj published Ornithological Works. 



wholly from the want of sufficient materials, the rule adopted 

 being that '^ every form whose characteristics bear unmis- 

 takably the impress of climatic or local influences, generally 

 less marked towards the habitat of another form with which 

 it thus intergrades, and all forms which certainly intergrade, 

 no matter hoAv widely distinct the opposite forms may appear, 

 together with intergrading forms whose peculiarities are not 

 explained by any known law of variation," should be " re- 

 duced to subspecific rank/^ 



On this we may remark, that we cannot deny the advan- 

 tages of the use of trinomials when strictly limited to such 

 cases as these, and have little doubt that they will ultimately 

 come into general use. But they can only be advantageously 

 employed in countries such as North America and Europe, 

 where large series can be obtained from many difi'erent loca- 

 lities. In other parts of the world their use would at present 

 be attended by much inconvenience, it being impossible to 

 ascertain in very many cases, from lack of specimens, whether 

 these intergradations exist or not. We may also remark 

 that other authors use trinomials on quite difterent principles, 

 e.g. Mr. Sharpe, who, in his last catalogue, has applied them 

 in some instances even to insular forms (which certainly can- 

 not intergrade) where the slight diff'erences are, in his opinion, 

 not strictly sufficient for specific distinction. 



The catalogue of names is followed by a very useful Ap- 

 pendix, in which taMes of various sorts contain a condensed 

 analysis of the changes that have taken place in American 

 ornithology since 1859, when Prof. Baird published the last 

 Smithsonian Catalogue of North- American Birds. Lists are 

 also given of unconfirmed, untenable, and introduced species, 

 which add greatly to the value of this laborious piece of 

 work. 



In conclusion, we think we may venture to make some 

 very small criticisms upon points of nomenclature, as we are 

 sure Mr. Ridgway is anxious to have his names as correct as 

 possible. 



Nos. 451 and 452. "Haliaetus'^ should be thus written, 

 or " Haliaetus," if the dieeresis be considered necessary. The 



