1926 ] 
The Affinities of Grylloblatta 
83 
than it is to the Acridids and their allies. The Gryllobiattid 
type of antenna approaches that found in certain primitive 
Dermaptera and Isoptera more closely than it does the Blattid 
or Mantid type of antenna, and the antennse of certain Grylloids 
and Tettigonioids are much more like the antennse of the Blattids 
and Mantids than is the case with the antenna of Grylloblatta, 
although in a few Blattids, I have found a suggestion of the 
Gryllobiattid type of antenna. 
It is quite possible that there were two tendencies in the 
Protoblattoid ancestors of the Orthopteroid insects. One ten- 
dency was to retain the multiarticulate type of antenna with 
many annular segments in the basal region of the flagedum while 
the segments in the distal region of the flagellum tended to 
become more cylindrical. This tendency, exhibited by most 
Blattids and Mantids, affected the development of the Grylloid 
and Tettigonioid types of antennae. The second tendency 
among the Protoblattoid ancestors of the Orthopteroid insects 
was toward a reduction in the number of antennal segments, 
and to increase the proportion of cylindrical segments, while 
only a few segments in the basal region of the flagellum remain 
short, or approach the annular type to any degree. This ten- 
dency affected the Phasmid, Dermapteran, and Gryllobiattid 
descendants of the Protorthopteroids more than any others. 
In the main, the evidence of the head-capsule and its ap- 
pendages is in harmony with that from other sources which 
supports the views as to the interrelationships of the Orthop- 
teroid and Isopteroid insects proposed by Crampton, 1924; and 
according to these views the insects in question were grouped as 
follows : 
Section Orthopteradelphia (Orthopteroid insects, sensu lato) 
Superorder Panisoptera (Isopteroid insects) 
Orders Protodictyoptera (Protoblattids — fossil) 
Dictyoptera (Blattids and Mantids) 
Isoptera 
Superorder Panorthoptera (Orthopteroid insects, sensu 
stricto) 
Orders Protorthoptera (Fossil) 
