118 PHILOSOPHY OF ZOOLOGY, 



Perhaps the terms anteal and retral may appear appro- 

 priate, the former expressing the extremity at the head, the 

 latter its opposite. 



The lateral plane is supposed to intersect the mesial plane 

 at right angles. Its extremities are designated by the same 

 terms ; but its edges are termed dextral or sinistral, accord- 

 ing as they are situated on the right or left sides, the hu- 

 man body being the standard. 



When the body is flattened along the edges of any of 

 these planes, there are particular terms used which express 

 this condition. Thus depression refers to a flattening on 

 the dorsal aspect, while compression indicates the flattening 

 to be on the side. 



The length of the body is usually measured along the 

 mesial, and the breadth across the lateral, plane. 



Instead of the terms internal and external, those of cen- 

 tral and dermal, or peripheral, have been substituted with 

 propriety. The term dermal applies to the skin, or exterior 

 covering of the body, or any organ ; while the term peri- 

 pheral expresses the surface of any included organ. 



All these terms, which thus end in ar or al, are adjec- 

 tives, and are restricted in their signification by the addi- 

 tion of the terms position, comiection, or aspect. Thus, the 

 orifice of an organ, with a central aspect, will indicate its 

 direction towards the centre. An organ having a sternal 

 position, is one situated at or near the sternum ; while ster- 

 nal connection would intimate its union with the sternum. 



As these terms frequently occur in composition, where 

 their use as adjectives would render circumlocution neces- 

 sary, the learned author of the work on Anatomical Nomen- 

 clature already alluded to, recommends their conversion into 

 adverbs, hy uniting to them the termination ad,{ox rather a^^, 

 which is similar). This, however, is a termination in the Eng- 

 lish language appropriated to substantives, and invariably 



