204 FRINGILLID^. 



the left as will be seen by the vignette (figs. 1, 2), and this 

 must be borne in mind, while following the description for 

 the maxilla as often as not curves to the right.* When the 

 bird is held in the hand, the point of the lower mandible, or 

 mandihula, can be brought immediately below that of the 

 maxilla, so as to touch it, but not beyond it towards the left, 

 while on its own side the point passes easily some three 

 eighths of an inch. The maxilla has a limited amount 

 of vertical motion, the union between the nasals and the 

 frontals being a flexible lamina. The transpalatal pro- 

 cesses are considerably prolonged downwards (fig. 3, a) 

 affording space for the attachment of large pterygoid muscles. 

 The pterygoid itself (fig. 3, h) on each side is strongly arti- 

 culated to the quadrate (fig. 3, c), affording firm support to 

 the movable portion of the maxilla. The jugal (d), which 

 is united to the maxillary in front, is firmly attached by its 

 hinder end to the outer side of the quadrate. When there- 

 fore the last is pulled upwards and forwards by its own pecu- 

 liar muscles, to be after described, the jugal on each side by 

 its pressure forwards raises the maxilla. 



The lower process of the quadrate forming the condyle to 

 which the mandibula is articulated is in very many birds 

 somewhat linear from before backwards, admitting only ver- 

 tical motion ; but in the Crossbill this process (fig. 3, c) is 

 spherical, and is received by the lower jaw in a hollow cup 

 (fig. 5, a), so that the articulation possesses much of the 

 universal motion of a ball-and-socket joint. 



The mandibula is of great strength with prominent coro- 

 noid processes (fig. 5, h, h), to which, as to the whole outer 

 surface of its hinder portions the temporal muscles are 

 attached. The temporal and pyramidal muscles on the right 

 (that being the side to which the mandibula inclines) are 

 considerably larger than those on the left (tigs. 1, 4, a, h). 

 The pterygoid muscles (fig. 2, c, c) are also very large. 



The muscles depressing the mandibula are three in number, 

 but only one of them, the great pyramidal, is shewn in the 



* The opinion, now generally acknowledged to be erroueous, used to prevail 

 that the sexes in the Crossbill might thus be distinguished. 



I 



