THE ENGLISH SPARROW. 229 



2. The postorbital process of the frontal bone, projecting 

 downward to form the postero-lateral rim of the orbit. 



3. The squamosal bone, applied obliquely to the side of 

 the cranium, just behind the postorbital process of the 

 frontal. 



4. The quadrate bone, a conspicuous bone connecting 

 the lower jaw with the cranium, and freely articulated 

 with both. 



On the ventral surface of the skull, anterior to the occip- 

 ital, are three distinguishable unpaired bones. 



1. The basisphenoid forms the convex, most ventral 

 portion of the cranium. 



2. The rostrum is the narrow forward continuation of 

 the basisphenoid, and appears as a thickening of the ven- 

 tral edge of the interorbital septum. 



3. The ethmoid is a small bone inclosed between the 

 nasals and the lachrymals, and lying on the median line, 

 at the anterior end of the rostrum. 



The remaining bones of the ventral side of the skull are 

 paired. They form two bony bars on each side, extending 

 from the premaxillary in front to the quadrate behind. 

 The premaxillary of each side on its ventral surface will 

 be seen to send back two short horizontal processes of bone, 

 one to meet each of these bars. 



1. The outer or quadratojugal bar is a slender rod of 

 bone forming the ventral border of the orbit. It extends 

 from the outer or maxillary process of the premaxillary 

 bone to the quadrate. It is composed of three bones 

 wholly indistinguishable in the adult skull. These are 

 (named from the front) maxilla, jugal, and quadrato- 

 jugal. 



2. The inner or palato-pterygoid bar is composed of the 

 palatine and pterygoid bones, and extends from the inner 

 or palatine process of the premaxillary back to the quad- 

 rate. It is not a straight and simple bar of bone, like the 



