( 'C^ ) 



angular process is more nearly vertical, and it projects to a less degree posteriorly 

 and more ventrally than that of the JIauritian bird. The points of difference from 

 Erythromachus are much the same. 



As already mentioned, there is considerable individual variation in size, both in 

 the skull and other portions of the skeleton of this species. Indeed Mr. Forbes has 

 suggested that there may really be several distinct species. 15ut e.xamination of more 

 than twenty skulls and a very large series of limb-bones shows that there is, in fact, 

 only one, the interval between the largest and the smallest individuals being completely 

 bridged over by many intermediate varieties. The table appended will give some idea 

 of the variations in the size of skull and mandible : — 



Numbers marked with an asterisk are only approjtimate. 



The skulls in columns 3 and s, and mandibles in 3 and 1, are in the Britislj Museum. 



These considerable indi\idual difierences in the size of the .skull and mandible 

 are accompanied by equal differences in the dimensions of the other portions of the 

 skeleton, measurements of some of which will l)e given below. 



Most flightless birds apjiear to be suljject to this great variability ; for instance, il 

 is well marked in Didus, Pezophnps* Erylhromachim, and among the Dinornithidae, 

 although in the last case its e.xtent is a.\A to be imdere.slimated, owing to the practice 

 of giving distinct names to forms differing slightly in size only. Its cause must be 



• Sec A. and E. Newton, •■ On the Osteology of the Solitaire " (/'//«. rriiiig. Vol. fl.l X. 1869. p. 336), 

 where the probable cause of this variation is discussed. 



