THE USES OF COMPARATIVE ANATOMY. 233 



Com'missures. The point of union between two parts; thus 

 the commissures of the eyelids, lips, &c., are the angles which 

 they form at the place of union. 



Comparative Anat'omy. The science which treats of the 

 structure and relation of organs in the various branches of 

 the animal kingdom^ without a knowledge of which it is hn- 

 possible to understiind the beautifully progressive develop- 

 ment of organization, necessary even for the full comprehen- 

 sion of the uses of many parts of the human body, which, 

 apparently rudimentary and useless in man, are highly de- 

 veloped in other animals. This science is also the basis of 

 physiology and the natural classification of animals. 



Amsrkan Oyelopedia. 



Con'dyle. An articular eminence, round in one direction, flat 

 in the other. A kind of process, met with more particularly 

 in the ginglymoid joints, snch as the condyles of tlie occipi- 

 tal, inferior maxillary bone, &c. 



Congen'ital (from con and genitics, 'begotten'). Diseases 

 which infants have at birth ; hence, congenital affections are 

 those that depend on faulty conformation, as congenital her- 

 nia, congenital cataract, &c. 



CoNJUNCTi'vA Membra' NA. A mucous membrane, so called 

 because it unites the globe of the eye with the eyelids. It 

 covers the anterior surface of the eye, the inner surface of the 

 eyelids, and the ' caruncula lachrymalis.' It possesses great 

 general sensibility, communicated to it by the fifth pair of 

 nerves. 



Copyba'ra is the largest known quadruped of the order Ro- 

 dentia, and belongs to the family Cavidse. It is an aquatic 

 animal, a native of Soath America, and feeds on vegetable 

 food exclusively. Its dentition resembles that of the cavy, 

 except that the grinding teeth are formed of many trans- 

 verse plates, the number of plates increasing as the animal 

 advances in age. It is inoffensive and easily tamed. The 

 flesh is esteemed good food. It is somewhat smaller than 

 the common hog. Johnson's New UnideTsal Gydapedia. 



COR^PUSCTLE. One of the ultimate morphological elements of the 

 body. They exist at some time or other in all the tissues of 

 the body, governing their vital actions. The white and red 

 corpuscles of the blood, epithelial bodies and ganglionic nerve 



