No. I.] CONTRIBUTION TO INSECT EMBRYOLOGY. J J 



While studying the movements of the embryo and the for- 

 mation of the envelopes in the different orders and families of 

 insects, with a view to testing the current classification, which 

 is the outcome of a great amount of comparative anatomical 

 and paleontological work, I have been especially impressed 

 with two facts : First, the embryological data in no wise conflict 

 with the generally accepted classification of Brauer. The de- 

 velopmental variations within limited groups are never greater 

 than the post-embryonic differences in the members of the 

 same groups. Usually there is great uniformity in embryo- 

 logical development between systematically allied insects of 

 the same order ; the wide gaps usually occur between the 

 orders just where gaps have long been pointed out by com- 

 parative anatomy and paleontalogy. Second, developmental 

 differences between members of different allied families of 

 Orthoptera are greater than the differences between remotely 

 related families in more recent orders. For example, the dif- 

 ferences between a Locustid and an Acridian or a Locustid 

 and a Gryllid embryo, or between any of the Saltatoria and 

 the Blattidae, or Mantidae, are greater than the differences be- 

 tween an embryo Hydrophilid and a Chrysomelid, a Tabanid 

 and a Chironomid, or a Bombycid and a Shingid. Frequently, 

 it is true, the differences between the extremes in the higher 

 orders are considerable, as between the Tenthredinidae and the 

 Proctotrupidas among Hymenoptera, or the Chironomidae and 

 Muscidae among Diptera. If any conclusions bearing on classi- 

 fication can be drawn from the few embryological data which 

 I have collected, they refer to the ordinal value of the vari- 

 ous Orthopteran families. It would appear that these groups 

 have really more than family value. They are older than the 

 families of more recent groups, and therefore exhibit greater 

 divergence. The Rhynchota will probably be found to present 

 conditions similar to the Orthoptera. There are certainly more 

 considerable differences between the embryos of such forms as 

 PyrrJiocoris and Ranatra than there are between the embryos 

 of widely separated families among the Coleoptera. 



