338 ENTOMOLOGICAL NEWS [Oct., '15 



nectent insect, and would add the following details to the ex- 

 cellent general description he has already given of it. 



In making a comparative morphological study of various in- 

 sects in connection with the preparation of a paper dealing 

 with the ancestry and affinities of the Hexapoda, it has become 

 apparent that an attempt to trace the genealogy or relationships 

 of insects largely through the study of their wing-venation 

 is of little value. The study of no one structure or organ 

 should be made the basis of such a work; and furthermore, 

 the study of wing venation would be of no value in connection 

 with larval forms, or with apterygote insects. In addition to 

 this, some of the most important annectent forms (such as 

 ArLrenia, Grylloblatta, etc.) have lost their wings, and in such 

 cases, a study of wing-venation would be quite useless. I have 

 therefore laid greater emphasis upon the study of the head 

 and terminal abdominal structures, and the thoracic sclerites 

 (together with the parts of the legs), relegating the wing-ven- 

 ation to a position of secondary importance. 



The accompanying figures of the thoracic sclerites of Gryl- 

 loblatta, are of necessity somewhat "diagrammatic," since 

 it was not always possible to clearly distinguish the outlines of 

 the plates in a delicate insect which had been allowed to dry 

 before it was placed in alcohol ; and fear of injuring a valuable 

 specimen prevented a thorough examination of parts concealed 

 by overlapping structures. Subsequent examination of speci- 

 mens preserved in alcohol, however, will, I think, demonstrate 

 that the figures here given, are in the main correct. The ter- 

 minology here employed, is that used in former papers deal- 

 ing with the comparative anatomy of the thoracic sclerites 

 (e. g. "Notes on the Thoracic Sclerites of Winged Insects:" 

 Entomological Nezvs, Vol. xxv, Jan. 1914, pages 15-25). 



The thorax of Grylloblatta presents a curious combination 

 of characters also found in the Dermaptera, Isoptera (which 

 are related to the Dermaptera as well as to the Blattids) and 

 Gryllidae. As shown in PI. XIII, Fig. i, the outline of the 

 pronotum (pr), mesonotum (mes) and metanotum (met} is 

 quite like that of the nota of' such wingless Dermaptera as 



