256 ENTOMOLOGICAL NEWS. [June, 'l6 



the ancestral Pterygota, I do not think that there was as direct 

 a line from the ancestors of the Dicellura to those of the Der- 

 maptera, or from the ancestors of the Protura to those of the 

 Plecoptera, as my former statements would lead one to infer, 

 and I would prefer to explain the similarities between the Di- 

 cellura and Dermaptera, or between the Protura and Plecop- 

 tera, as follows: 



The Forficulid and other lines of development of the Or- 

 thoptera-like groups converge either toward the Perlid, or the 

 Blattid line of development; and both the Perlid and Blattid 

 lines ultimately lead back to, or closely parallel, the Lepismid 

 line of descent. Ultimately we reach the more remote ancestral 

 group containing the common ancestors of the Lepismid, Blat- 

 tid and Perlid lines of descent. If we trace the lines of de- 

 velopment of this ancestral group still further back, we find 

 that the more remote ancestors of the forms giving rise to the 

 Lepismid line of descent, in turn possessed many characters 

 common to the remote ancestors of the Japygid, Proturan, and 

 other Apterygotan groups ; and the common ancestors of all 

 these were doubtless so similar that they might be classed in 

 a single family or even sub-family. From this common ances- 

 tral stem-family there arose the various lines of descent lead- 

 ing to the different Apterygotan and Pterygotan groups of in- 

 sects ; and since all these lines have a common origin, it 

 is merely to be expected that the Forficulids, for example, 

 might retain certain features which have also been retained 

 by the Japygids, or that the Plecoptera might have retained 

 certain features which have also been retained by the Pro- 

 tura, etc. The resemblances between the Japygids and For- 

 ficulids, or those between the Plecoptera and Protura, might 

 therefore possibly be regarded as due to the retention in each, 

 of certain features derived from their ancient common ances- 

 tral stem group, rather than due to the fact that they indicate 

 that there are distinct lines of descent leading from the imme- 

 diate ancestors of the Japygids to those of the Forficulids, or 

 from the immediate ancestors of the Protura to those of the 

 Plecoptera, etc. At any rate, the ancestors of the Forficulids 

 and Plecoptera were too closely related to be descended from 



