ANSEKES 



457 



figures the gizzard and windpipe, that there are noteworthy 

 modifications of structure. The bird flies strongly when 

 young, but swims only when adult. Cunningham suggests 

 a greater density of the bones ; but when weighed and com- 

 pared with the skeleton of some other Anseres no reliable 

 differences were apparent. 



Gnemiornis calcitrans is a large anserine bird from the 

 Pleistocene deposits of New Zealand, which, according to 

 Sir James Hectoe,^ stood over two feet high, and was at 

 least three feet in length. Gnemiornis is characterised by 

 the great weight of its bones ; the following comparative 

 table from Hector's paper brings out this fact : — 



It seems clear from these comparisons that Gnemiortiis 

 could not have been a flying bird. Moreover the sternum 

 has a keel whose highest elevation is under three hnes. 

 This bone appears to have possessed no lateral notches, but 

 only a slight median concavity. On the other hand the 

 ' rough tubercular surface ' of the keel is perhaps a little 

 suggestive of a missing cartilaginous piece. 



The suggestion of Furbeinger to separate Gnemiornis 

 into a sub-family, Cnemiornithinse, seems perhaps, in the 

 light of the above facts, to be justifiable. But the remainder 

 of the members of the family cannot be divided with precision. 

 It is above all impossible to divide swans, geese, and ducks 

 from each other into three such groups. Nevertheless, as 

 will be gathered from the following account of their struc- 

 ture, the Anseres vary very much among themselves — more 

 especially in the structure of the windpipe. 



All the Anseres, as noted in the definition, have a tufted 

 oil gland. 



' ' On Cnemiornis calcitrans,' &o., P. Z. S. 1873, p. 768, and 1874, p. 307. 



