THE CANADIAN ENTOMOLOGIST 213 



A COMPARISON OF THE ANTENNA OF THE GRYLLO- 



BLATTID.E AND EMBHD.F: TO DEMONSTRATE 



THE RELATIONSHIP OF THESE TWO 



GROUPS OF INSECTS. 



BY G. C. CRAMPTON, PH. D.*, AMHERST, MASS. 



It has been maintained that the Grylloblattida are descended 

 from Blattid-like forms, by some investigators (Walker, 1914, 

 and others), while the writer (Crampton, 1915-1916) would derive 

 them from Plecoptera-like forebears, through Embiid-like ances- 

 tors. It is of the utmost importance to determine the exact affiini- 

 ties of the Grylloblattids, if we wish to trace the genealogy of the 

 Orthopteroid groups (i. e., the Tettigonids, Gryllids, Locustids, 

 etc.) since the Grylloblattids have departed the least of any living 

 insects from the ancestral condition of the Orthoptera and their 

 immediate relatives, and, therefore, furnish us with the most re- 

 liable evidence available for determining the affinities of Orthop- 

 teroid insects. On this account, I would present the evidence to 

 be gained from com_parative anatomy, in a series of papers in which 

 the various external structures of the Embiids and Grylloblattids 

 are compared part for part, in an endeavor to demonstrate that 

 the Grylloblattids are more closely related to the Embiids than to 

 any other group of lower Pterygotan insects, and that the Gryllo- 

 blattids are consequently to be derived from Plecoptera-like 

 ancestors through more immediate ancestors which closely re- 

 sembled living Embiids. 



In the present paper, which is the first of the series, I would 



present the evidence of close relationship between the two groups, 



to be gained from a comparison of their antennae. Unfortunately, 



the accompanying rough sketches were made from loaned material, 



at a time when I did not realize the importance of making a more 



detailed study of the antennae, since the specimens were borrowed 



primarily for the purpose of examining the thoracic sclerites — 



which furnish one of the most reliable sources of determining the 



relationships of insects, from the standpoint of comparative 



anatomy. The drawings, however, will be found sufficiently ac- 



c urate for all practical purposes. 



* Contribution from the Entomological Laboratory of the Massachusetts 

 Agricultural College, Amherst, Mass. 

 Tune, 1917. 



