DISCOVERIES IN AVIAN PALAEONTOLOGY. 409 



that of all the genera Mesopteryx is considered to be the 

 least specialised, and retains most nearly the ancestral 

 characters of the family. At the same time it was also 

 shown that some species probably possessed a frontal 

 crest of large feathers, the points of insertion of which 

 are marked by a series of pits on the cranial surface ; in 

 some cases this character seems to have been a sexual one. 



In the same year Hutton (23) published a paper which 

 may be regarded as an appendix to his important memoir, 

 "On the Moas of New Zealand," which appeared in 1892, 

 and consequently does not fall within the scope of the 

 present review. In this appendix the author states that in 

 his opinion it is necessary to subdivide the various genera 

 of the Dinornithidae into more species than had hitherto 

 been done ; since it is only by keeping the various species 

 and varieties distinct, that the relative ages of the various 

 superficial deposits in which their remains occur can be 

 ascertained. The method of subdivision employed by 

 him seems, however, to be open to the objection that it 

 is an extremely arbitrary and artificial one, for in his former 

 paper above referred to, as well as in the present one, he 

 relies mainly, and in many cases entirely, on measurements 

 of the long bones for separating the species. When we 

 consider that it is possible to trace an almost complete 

 gradation in size between the larger and smaller specimens 

 of any given bone, it is clear that the number of species 

 into which the series is divided, will depend upon personal 

 opinion as to the latitude to be allowed for individual 

 variation. In some cases where small differences in size, 

 accompanied by other slight variations, are constant in two 

 forms from different localities, the careful records and 

 measurements given by Professor Hutton are of much 

 interest and importance, but even in such cases it seems 

 better to regard such small differences as indicating local 

 races rather than distinct species. 



Dr. H. O. Forbes (24) has severely criticised Professor 

 Hutton's methods, and points out that in some cases the 

 measurements given for one species fall within the limits 

 assigned to another. 



