170 Prof. Owen on a Species of Parrot. 



margin, which is thinned off to an edge, there are, as in the 

 Maccaws and Parrots, grooves and foramina for the small 

 nerves and vessels of the formative part of the horny beak- 

 sheath. 



But the most decisive test of the nature of the present 

 fragment is afforded by the characters of the upper or inner 

 surface (fig. 2). This, of course, is concave transversely, and 

 shows a more regular upcurving of the sides of the gonys 

 than the external surface does. It is marked by the curved 

 line, convex backward, which, commencing from near the an- 

 tero-lateral angles of that surface, extends to a shallow sub- 

 circular depression in the posterior third part of the symphysis. 



Fie:. 4. 



Upper or inner view of lower jaw, Ara mucao (Linn.). 



A pair of minute foramina marks the anterior border of this de- 

 pression. The curved line, in recent Parrots (fig. 4), marks the 

 posterior extent of the thin internal horny plate of the sheath of 

 the lower mandible. 



In size the Mauritian Cockatoo, represented by the above- 

 described fragment of skeleton, appears to have equalled the 

 Hyacinthine and Blue-and-yellowAras, or Maccaws (figs. 3 and 4), 

 and the larger Cockatoos {Microglossa) of Australia. Mr. Gould 



