58 



Recent Literature. [j*n. 



He says : "Mimicry, with the prefix unconscious, which in every depart- 

 ment of Zoology should he always expressed or understood, signifies the 

 more or less complete likeness, in colouring or form or hoth, which one 

 creature bears to another, so that in some cases one may easily be 

 mistaken for the other, though the affinity between them may be very 

 remote .... The explanation is simply that the weaker animal, or that 

 which exists under less favorable conditions, 'mimics' the stronger, or 

 that which is most flourishing, the mimicry being presumably effected by 

 means of Natural Selection ; but the difficulties which attend the investiga- 

 tion of the way in which this result is brought about, so as to render the 

 explanation in all cases acceptable, are often extremely great, and one 

 ought not to be surprised that some zoologists are unable to accept the 

 explanation at all." As one of the conditions for an acceptable case of 

 mimicry, as laid down by Wallace, is that the mimicker and the form 

 mimicked must both share the same habitat, Prof. Newton finds it con- 

 venient to cite only about three or four good examples among the class of 

 birds, — that of "a Cuckow to a Hawk," that of Mimeta (a genus of 

 Orioles) to Philemon (a genus of Friar-birds), that of Harpagns diodon 

 to Accipiter pileatus (a very weak case), and that of the genus Tylas to 

 Xenofirottris. None of them very fully meets the conditions of a good 

 case of mimicry, since the advantages secured by the supposed mimicry 

 are by no means very obvious. The most that can be said is that the two 

 forms which present a somewhat striking superficial resemblance to each 

 other happen in each case to occupj a common habitat. A large number 

 of other cases might be cited were it not for their dissimilarity in distribu- 

 tion, and a number of such are mentioned passim in the 'Dictionary,' as 

 Agapornis and Psit taenia, Alirmou and L//>u/<ir, Sturnella and Macrouyx 

 Serifbpkus and Ampelis, Colaptes ami Geocolaptes, etc., while the list 

 could easily be greatly extended. Hence our author feels called upon to 

 caution his readers to hear in mind "that all cases of close similarity of 

 plumage are not necessarily Mimicry." There is not space here to discuss 

 the subject at length (as we hope to do later in some other connection), 

 but it may Ik- well to suggest that there is another side to the question, 

 ami that there are other explanations of these resemblances that seem 

 more reasonable. In fait in most instances, and at least so far as birds 

 are concerned, it seems by no means rash to consider them as purely 

 accidental, or cases of coincidence. ' 



The article on 'Geographical Distribution' is an admirable presentation 

 of the subject, although on minor points we should find it somewhat diffi- 

 cult to subscribe to all of our author's conclusions. We notice, with some 

 surprise, the absence of any discussion of the causes, past or present, of 

 the distribution of avine life, except incidentally in one or two cases. It 

 may be noted that a number of important departures are made from the 



'See further the discussion of 'Mimicry' in Beddard's 'Animal Coloration,' and the 

 evidence and authorities, pro and con, there cited. 



