( 393 ) 



Professor Parker's statement that " in ^1. Oweni . . . the emargination of the 

 anterior border ... is slightly sinnous, each side presenting a sigmoid curvature." 

 I have not found this characteristic form of the anterior emargination of the 

 sternum in any species but ^l. owcni. 



4. There are occasionally but rarely two fenestrae in the sternum. Owen 

 describes this in his specimen of ^1. australis ; I have seen the same thing, the 

 right fenestra being rather the larger in an A.mantelli. In another A. tnantelli 

 there were two minute fenestrae of pinhole size. 



5. The sternum of Apteri/x is described as quite flat and keelless. Nevertheless 

 T. J. Parker observed in quite a large proportion of examples of ^1. mantelli studied 

 by himself a distinct keel. I also find it to be commonly present in that species. 

 This vestigial keel is so slight that it is not particularly easy to see ; it is however 

 readily y^/^ I have found similar traces in A. haasti. 



6. From measurements of the sternum Professor Parker thought himself 

 justified in deducing the following results : — 



" In A. australis the length of the corpus sterni appears to be constantly more 

 than half its breadth." 



"In ^1. bulleri (= A mantelli) the length of the corpus sterni is — often con- 

 siderably — less than half its breadth." 



" In A. oweni . . . the length of the body is less than half its breadth." 

 I have tested these conclusions upon other examples measured in precisely the same 

 fashion as that adopted by Parker. These are my figures : — 



These measurements on the whole bear out Professor Parker's remarks con- 

 cerning.!, oweni &\iA A.mantelli. I may perhaps point out in addition that^l. hdasti 

 belongs to the same category as those two species, but that there is a tendency to an 

 increase in the length as compared with the breadth. In A. australis it appears from 

 the measurements which I have taken that the length is also less than half the 

 breadth. But not a great deal can be made out of these measurements. In the 

 first place the nnmbers (actual and proportional) are very close ; the difierencos are 

 not at all salient. In the second place the occasional asymmetry of the lateral 

 notches renders it sometimes difficult to follow out Professor Parker's scheme of 

 measurements. I give my own figures therefore for what they are worth, which 

 does not appear to me to be a great deal. 



Skull. 



The very slightest differences apart from those of size distinguish the Apierygea' 



A peculiarity which I noticed in the skull of .4. australis is possibly of some 



little interest : that is, the bifid anterior extremity of the vomer, a deep oval notch 



