3899.] CRANIAL OSTEOLOGY OF THE PARROTS. 15 



in a broad, somewhat excavated shelf to overlap (as well as to 

 project in front of) the head and upper portion of the shaft of the 

 quadrate bone. This squamoso-zygomatic plate is deeply hollowed 

 on its outer face, suggesting perhaps the presence of a highly 

 specialized muscle (probably tbe secoad portion of the digastric) 

 originating there. The lower border of the overhanging shelf is 

 slightly bilobed, especially in another specimen in my collection from 

 that figured. The posterior portion or posterior lobe, and perhaps 

 the whole hollow on the outer face of the bone, may be considered 

 to be an extension of the region internal or anterior to the " supra- 

 meatal " process of Mivart, a region which in most Parrots forms 

 only a small facet; its aspect here, together with the general 

 conformation of the bone, reminds us how in a Lizard the squa- 

 mosal tends to overlap the outside of the quadrate in a way which 

 eiilminates in the great descending limb or process of the bone 

 that bounds the infratemporal arcade in Hatteria. 



I know no other bird in which a very similar condition of things 

 is to be seen ; but we may discover in some Passerines, e. g. the 

 Raven, a certain correspondence of parts. 



If we trace in the Eaven (fig. 4) the ridges and muscular im- 

 pressions on the postero-lateral surfaces of the skull, we see (1) on 

 the upper margin of the supra-occipital region two curved trans- 



Fig. 4. 



Corvus corax, to show diagrammatically the muscular fossae and 

 intervening ridges. 



S.m., suprameatal tubercle ; sq^., squamosal ; t. temporal, d. digastric fossa ; 

 d.\ fossa for second head of the digastric, in front of a.m., the suprameatal 

 tubercle. The ridges or outlines of the muscular impressions are described 

 in the text. 



verse ridges which run outwards from the middle line to a tubercle 

 (a) posterior to and nearly on a level with the upper border of the 

 auditory meatus ; (2) an undi^'ided ridge curves downwards from 



