TERMINOLOGY 37 



and posterior as applied to a lower form. Since it is unwise to 

 change the form of the official terms of human anatomy, it becomes 

 necessary to interpret all such terms when used for a quadrupedal 

 mammal according to the relations exhibited by man. The human 

 terms may in most cases be translated into terms acceptable for 

 comparative anatomy by reading ventral for anterior, dorsal for 

 posterior, cranial or oral for superior, and caudal or aboral for 

 inferior. The exceptions then apply to those parts of the body 

 unaffected by rotation. 



On the other hand, in ordinary description of organs and their 

 position, where it is not a matter of the official names of parts, little 

 advantage is to be gained from adherence to this principle. The 

 terms anterior and posterior apply with much greater force to a 

 lower vertebrate than to man, while the terms superior and inferior 

 are of interest only in the latter. In this case the rule here followed 

 is to use the terms anterior and posterior for descriptive purposes 

 without reference to the human relation. The same remark applies 

 to the terms of direction, viz., upward, downward, forward, and 

 backward. 



In this connection it may be pointed out that the custom has 

 become more or less general in comparative anatomy of employing 

 the termination ad with words otherwise signifying position alone, 

 in order to indicate position or course toward, e.g. dorsad = 

 dorsalward. In the present case this form is used only for course^ 

 position being indicated by the adverbial termination ly, e.g. 

 dorsally. 



Reference may also be made here to the fact that the human 

 structures to which identifying names are applied frequently fail in 

 one way or another to correspond to structures in a lower form. 

 Composite structures to which individualizing names are applied, 

 for example, may be represented by independent parts. Also, 

 structures which are similar in form or function may be convergent. 

 Finally, although it is essential to endeavour to apply all terms as 

 accurately as possible, it will be remembered that a terminology 

 primarily arranged for one type cannot be exactly applied ta 

 another without considerable qualification. 



