ANATOMY. 295 



take advantage of them as fulcra to display propulsive 

 force. 



In the contemplation of reptiles and birds, we 

 perceive that they possess wide jaws. The peculiarity 

 is to give these creatures faucial capacity; and if we 

 give attention to skeletal parts, an extra bone will be 

 found near the ear; this is the os quadratum quad- 

 rate bone placed at the base of the skull to receive 

 the articulation of the under jaw. ~No mammal pos- 

 sesses such an arrangement to give width to the throat. 

 Birds have the two clavicles joined in the median line 

 near the keel of the breast-bone, and the two branches 

 thus united constitute the furculum, or "wish-bone." 

 Extending from the breast-bone upward and outward 

 to the head of the scapula, in birds, is a strong bone 

 not found in the mammal skeleton. This at -first was 

 a puzzle for comparative anatomists, but it is now as 

 well understood and as rationally explained as any 

 part of the skeleton. It is the eoracoid bone the 

 coracoid process of the scapula specialized, or de- 

 veloped enormously for a particular purpose that of 

 forming a buttress for the support of the wing. 



In making even a slight examination of the ani- 

 mal kingdom, it is easy to see that one species or order 

 of animals grades or gradually shades into another; 

 that there is a blending of features at more or less 

 points in their organization. If it were not for the 

 disposition to vary, the world would present a same- 

 ness that would be wearisome. However, in extreme 

 variances it is not always easy to account for so much 

 swerving from typical forms, unless something besides 

 utility be gained in the extraordinary development of 

 parts. The huge ears of an ass do not render the 

 animal's sense of hearing more acute, and the auricu- 



