LEE BARKER WALTON 77 



arising in connection with the dorsal and ventral bundles 

 of setx and corresponding to the outer (ectal) and inner 

 (endal) groups of sclerites as outlined above. It would 

 thus appear that the Arthropoda are a polyphyletic 

 group, and that the relationship between the appendages 

 of the Hexapoda and Crustacea is a more remote one than 

 generally accepted in connection with the studies of 

 Hansen and Borner. 



The historical development of the problem as well as 

 the presentation of the facts which would seem to estab- 

 lish the views here advanced, will appear in the completed 

 paper of which this is a partial summary. 



Discussion: W. A. Riley — I have been especially interested to learn 

 that Dr. Walton is swinging away from his earlier belief in the double 

 nature of the insect segment. It has seemed to v%e that embryological 

 data afforded no evidence in stipport of the theory though there are 

 indications of the biramous nature of the appendages. The theory of 

 the origin of the insect appendages front the pleiiropodes receives much 

 additional support from the work here presented. 



