64 ENTOMOLOGICAL NEWS [Mar., 'iQ 



Notes on the Phylogeny of the Orthoptera.* 

 By G. C. CRAMPTON, Ph.D. 



(Continued from page 48.) 



Structures which are of but little importance to the life of 

 the organism, are not greatly affected by natural selection ( or 

 by use and disuse, if these are factors in evolution) and are 

 among the least-varying structures within an order or super- 

 order of insects. It is just these structures, however, which 

 are of the utmost phylogenetic importance, since their reten- 

 tion is almost wholly due to heredity alone, and on this ac- 

 count I would lay much greater stress upon the evidence af- 

 forded by such structures than upon those which are of greater 

 value in the struggle for existence (and hence subject to its 

 modifications), yet vary a great deal even within the same order 

 of insects. Such structures which furnish very serviceable 

 clews as to the interrelationships of the orders of insects are 

 the cervical sclerites or neck plates, which are remarkably 

 constant within an order, or even superorder of insects, and I 

 have therefore laid greater stress upon the character of the 

 cervical and prothoracic sclerites than upon any other one set 

 of structures, although unless supported by the evidence 

 drawn from many other sources as well, the evidence afforded 

 by these structures alone would be wholly inadequate as is 

 true of any one set of structures taken alone. 



In Vol. 28 (p. 393) of Ent. News for 1917, it was shown 

 that the lateral neck and prothoracic sclerites of Grylloblotta 

 are astonishingly like those of the Embiids, even in regard to 

 the minutest details and the resemblance cannot therefore be 

 attributed to a mere convergence (parallelism) in develop- 

 ment. Such a resemblance in these unimportant and little- 

 varying structures can only mean that these types of sclerites 

 were inherited froir a common ancestry. While the antennae 

 may vary considerably within an order, or even family of in- 

 sects, the remarkable resemblance (even in the matter of the 

 relative lengths of the segments, etc.) between the antennae 



* Contribution from the Entomological Laboratory of the Massachu- 

 setts Agricultural College, Amherst, Mass. 



