ß32 ^'■- HANS GADOW, 



and socket Joint, specially in a lateral direction, in Opposition to the 

 chiefly vertical motion of the mandibles of raost other birds. 



„When holding the head of this bird in my fingers, I found I 

 could bring the point of the under mandible in a line underneath and 

 touching the point of the upper, but not beyond it towards the left side, 

 while on its own side the point passed with ease to the distance of 

 '^Ig of an inch" (Yarrell). 



The principal food of the Crossbills consists of seeds of Conifers, 

 but other seeds like those of apples are likewise taken. Their mode 

 of feeding is this: „They fix themselves across the pinecone, then 

 bring the points of the maxillae from their crossed or lateral position, 

 to be inmediately over each other. In this reduced compass, they 

 insinuate their beaks between the scales, and then opening them, 

 not in the usual manner, but by drawing the inferior maxilla side- 

 ways (and by energetically turning their heads) force open the scales 

 or squamae" (Townson). Thereupon, whilst the points of the beak press 

 the Shell from the body of the cone, they insert the scooped end of 

 their tongue underneath the seed, and the food thus dislodged is 

 transmitted to the mouth (Yarrell). 



I have examined a nestling of Loxia curvirosiris. Not yet fledg- 

 ed it had not been able to leave the nest; its stomach contained the 

 unhusked seeds of some species of Conifer. These seeds must have 

 been collected by the parents and brought in their crops to the young. 

 The beak of the young bird (Fig. 4) is still somewhat soft, the horny 

 sheath of the jaws is not yet protruded into curved points, the 

 cutting edges are still straight, not beut inwards. Whilst the upper 

 beak is still quite symmetrical, the lower jaw is, when viewed from in 

 front, seen to be slightly turned to the right, so that its tip deviates 

 not more than one millimeter from the middle line. The cranium 

 and the quadrato-mandibular apparatus do not show any asymmetry 

 in size and shape. 



Consequently the distortion of the beak increases with the age 

 of the bird to such an extent that it even affects a considerable portion 

 of the skull in a secondary way, and it is produced by the frequent 

 oblique pressure upon the tips of the beak during the Operation of 

 opening the pinecones. 



This distortion which would have to be called pathological, if it 

 did not happen to turn out useful, begins to show itself, although 

 late, but still at a time when the young bird has not yet any necessity 

 of submitting its soft' jaws to any deforming strain. It can hardly 



