42 PROCEEDINGS OF THE ACADEMY OF [Jan., 



it would appear that these theories dealing with a change of function 

 have not been sufficiently well established, and it would be much 

 simpler to explain the origin of the cervical apodeme as a drawing 

 inward of a portion of the integument (or a corner of one of the sclerites) 

 due to muscular tension. 



Even if the theory of the tracheal nature of the cervical apodemes be 

 rejected, this does not preclude the possibility that the peritremal 

 sclerites which lay in front of the prothorax, may have taken part in 

 the formation of the cervical sclerites. The musculature of these 

 plates could admit of such an interpretation, and it would be only 

 natural that such sclerites should be the most developed in the cervical 

 region, where they would serve not only as supports for the attachment 

 of the head muscles, but also as strengthening plates for the membrane 

 of the neck. 



Verhoeff's, '02, theory seems very improbable from the fact that no 

 traces of a " mikrothoracic " segment are to be found in the embryo, 

 and none of the segmental structures show any indications of a dupli- 

 cation. On the other hand, if the theory that the cervical sclerites 

 represent the labial segment be accepted, how can one account for the 

 occurrence of similar plates in front of the meso- and meta-thorax, 

 for these surely cannot be likewise interpreted as labial segments? 



Voss, '04, attempts to show from the musculature that the cervicum 

 is the labial segment, but it would appear that the cervical muscles 

 are for the most part attached to the occiput, and not to the labium. 

 Furthermore, Riley, '04, himself states that the pleura of the labium 

 are in the occiput region, yet he speaks of the lateral cervicals as the 

 pleurites of the second maxillae, without giving any reason for thus 

 assigning them to the labial segment. 



It is possible that certain detached portions of the labial segment 

 may enter into the formation of the cervical sclerites, but it is not any 

 more correct on this account to designate the cervicum as the labial 

 segment, than it would be to term the intersegmentalia between the 

 first two thoracic segments, the prothorax. The ventral cervical 

 sclerites, termed by Comstock, '02, the labial sternum and sternellum, 

 appear to be detached portions of the prothoracic sternum, while the 

 lateral cervicals may possibly correspond to the "intersegmentalia" 

 between the pro- and meso-thorax, and the dorsal cervicals are probably 

 detached portions of the pronotum. 12 



12 In assuming that the cervicals are formed partially from prothoracic scler- 

 ites, it must be borne in mind that certain other factors, such as mechanical 

 friction, etc., may have produced certain of these sclerites. 



