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appendages of the body (legs, wings, etc.) the position of 

 parts may be referred to the two ends of the appendage by 

 use of the terms proximal and distal. Proximal indicates 

 nearness to the end of the appendage which is attached to 

 the body ; distal, to the end which is free. From these 

 adjectives the adverbs proximad (towards the proximal end) 

 and distad (towards the distal end) are formed. 



Examples. — The proximal segment of the leg of an insect is the 

 coxa. The segments of the leg distad of the tibia constitute the 

 tarsus. 



Aspects of appendages. — In addition to the two ends of 

 an appendage four aspects are recognized. To these the 

 same terms are applied as to the corresponding aspects of the 

 body: viz., dorsal, ventral, cephalic, and caudal. It is 

 therefore necessary to have a rule by which the correspond- 

 dence between the aspects of the body and of appendages 

 can be determined. In other words, a definite position must 

 be chosen as the normal position of an appendage. Naturalists 

 are quite well agreed as to what is the normal position of the 

 limbs of the Vertebrates. The following are what I believe 

 to be the analogous positions for the legs and wings of in- 

 sects.* 



(a.) Wings. — Extended horizontally at right angles to 

 the body as are the wings of a dragon-fly (Libellula) when 

 at rest. 



(£.) Legs. — Extended horizontally at right angles to the 

 body so that the convexity of the articulation between the 

 two principal segments of the leg (femur and tibia) shall 

 look dorsad ; and so that the surface of the tarsus ( ' ' foot ' ' ) 

 which is usually applied to the ground when walking shall 

 look ventrad. 



The dorsal, ventral, cephalic, or caudal aspect of a wing- 



* The necessity for referring to the aspects of other appendages than the legs 

 and wings will so seldom arise that it does not seem worth while to attempt to 

 determiue the normal positions of such appendages. 



