REVIEWS. 370 



exact relations that subsist between the average intensity of col- 

 oration of the birds that collectively inhabit the regions so defined. 

 We are gratified to find ourselves endorsed by Mr. Allen's inves- 

 tigations, as appears from the following paragraph : — 



" I had long snspected that hygrometric conditions had much to 

 do with local variations in color in individuals of the same spe- 

 cies, but I was not a little surprised when I came to compare the 

 known areas most prolific of dark or light local forms with rain- 

 charts — which maj^ be assumed as indicating relatively the hygro- 

 metric conditions of different regions — to find the distribution of 

 the light colored races so strictly coincident with the regions of 

 minimum mean annual rain-fall, and the dark forms with those 

 of maxinuun mean annual rain-fall, as seems to be the case. Hu- 

 midity has hence apparently more to do with climatic variation 

 than solar intensity." (p. 240.) 



Part III concludes with a vehement protest — certainly not 

 lacking in the force that comes of conscientious and earnest be- 

 lief — against the custom of naming forms, however distinct, that 

 are found to intergrade ; and at the risk of protracting this no- 

 tice beyond due bounds, we cannot, in justice to our author, refuse 

 to follow him further, although by so doing we must defer (per- 

 haps to take up in another connection), what we should wish to 

 say respecting Part V, in which the several bird-faunae of eastern 

 North America are defined. 



Mr. Allen undertook a laborious and not entirely grateful task ; 

 and has won enviable laurels in its execution. It is so discourag- 

 ing to the strongest swimmer to feel that he is breasting the tide 

 of nearly universal opinion, that moderate success must be corres- 

 pondingly acceptable. If it be something to deserve thorough 

 criticism it is more when close scrutiny detects nothing worse than 

 indiscretion. From the nature of his task, he was peculiarly ex- 

 posed to the danger of over-doing ; and in using the old maxim, 

 ne quid nimis, we indicate the pith of what adverse criticism we 

 feel compelled to make. In contributing invaluable material, care- 

 fully elaborated and forcibly presented, Mr. Allen seems neverthe- 

 less to have viewed his theme through the medium of enthusiastic 

 iconoclasm so refractive that he has lost some of his bearings, and 

 reached a position so extreme, that we fear ornithologists must 

 suspect his reasoning simply because his premises are unquestion- 

 able and his conclusions untenable. And what does he offer 

 instead of the idols he deposes ? After being shown what is not a 



