190 MR. H. E. STRICKLAND ON SOME BONES OF 



Large series. 

 Femur, No. 8. No. 9. 



Lines. Lines. 



Smallest circumference . . 29 30 ... 

 Tarso- metatarsus, No. 12. 



Lines. 



Total length 87 .... 



Smallest circumference . . . 234- .... 



But though the difference in size of the corresponding bones of these two series is 

 thus considerable, I have not been able to detect any diversity whatever in the propor- 

 tions of their parts. No question can possibly arise as to their generic identity ; we have 

 only to consider whether a diversity of size, amounting to the ratio of 4 : 3, suffices to 

 indicate specific distinctness. 



In the first place, it is evident that this difference of dimension cannot be due to age, 

 the smallest-sized bones affording the same proofs of complete maturity as the largest. 

 The small femur No. 16 in particular appears, from the rugose condition of its surface, 

 to have belonged to an aged individual. Nor is it, I think, probable that these differences 

 of size can be sexual. "Were these bones referable to the Gallinaceous order, we might 

 perhaps find examples in that polygamous group, of diversities of size in the two sexes, 

 sufficient to justify such a conclusion. But the bones in question have been satisfactorily 

 shown to belong to the order of Columhce (see 'Dodo and its Kindred,' pp. 54, 114), a 

 group in which the males and females present very nearly the same dimensions, and 

 certainly never vary in so large a ratio as 4 : 3". 



It seems to me equally impossible to believe that a difference of size amounting to 

 4 : 3 can come within the limits of ordinary or accidental variations in the same species. 

 Such varieties of stature, if they ever occur to this amount among birds of the same 

 species, are always due to pecuUarities of food or climate, operating at remote localities, 

 and never affecting the individuals inhabiting a small island, and all subjected to the 

 same external influences. I cannot therefore avoid the conclusion, that we have here 

 the proofs that two distinct species formerly inhabited the island of Rodriguez, differing 

 greatly in size, and probably (like other birds) exhibiting some other distinctions of 

 external appearance, of which no traces are left on the parts of their skeleton which 

 have been yet discovered. Should, however, the bones of the beak of these two supposed 

 species be ever obtained from the alluvia of Rodriguez, we may expect to find some 

 indications of specific distinctions depending on form as well as on size. 



In the work referred to. Dr. Melville and myself have uniformly spoken of the 



' Leguat's statement regarding the Solitaire, tliat " some of the males weigh forty-five pounds," certainly 

 indicates that the females were somewhat smaller ; but as he does not mention the weight of the latter, his 

 words prove nothing as to the amount of sexual disparity. 



