8oo THE AMERICAN NATURALIST. [Vol. XXXVIII. 



authors regard as homodynamous with the invaginations of the 

 lateral apodemes. Thus to these invaginations of the body wall 

 is ascribed a prime importance in determining the homologies of 

 the sclerites. Another valuable criterion they found in the rela- 

 tions of the appendages to a typical segment. 



In addition to limiting and carefully defining the sclerites 

 already -cncrally recognized, Comstock and Kochi also distin- 

 guished four pairs of sclerites which had previously escaped 

 attention. These were: ist, the antennal sclerites bearing the 

 antenna; ; 2nd, the antecoxal pieces of the mandibles, a pair of 

 sclerites in some species distinct from the clypeus and forming 

 the ventral articulations of the mandibles; 3rd and 4th, two 

 pairs of maxillary pleurites, narrow, chitinized bands between 

 which articulate the cardines of the maxilte. In addition to 

 these four pairs of sclerites proper, there are two pairs which 

 may have originally represented segments of appendages. 

 These are: ist, the ocular sclerites, a pair of annular sclerites 

 bearing the compound eyes, and 2nd, the trochantins of the 

 mandibles, a pair of sclerites between the mandibles and the 



1 hen- conclusions regarding the relations of the head sclerites 

 to the prmiitive segments and to the appendages were summar- 

 ized by Comstock and Kochi in the following table : 



(Deutocerebral) 



Clypeus proper 



Labrum (mouth) of Campode: 



Postgenae. 



