80 
Psyche 
[June 
mentioned above, but the Phasmid type although clearly derived 
from the same source, apparently follows a path of specialization 
leading to extreme development along the l'ne of massing the 
parts in the anterior region of the head, thus leading away from 
the common ancestral type from which the Grylloblattids and 
Dermaptera arose. The relation of the eyes and antennae, etc., 
to the bases of the mandibles is likewise very similar in the Em- 
biids and the forms mentioned above; but the Embiid type is 
evidently leading away from these Orthopteroids — although it, 
also, was evidently derived from Protorthopteroid prototypes. 
The study of the head capsule thus bears out the evidence 
from other sources indicating that the Grylloblattids, Dermap- 
tera and Phasmids are closely related, and sprang from a common 
Protorthopteroid ancestry; and these in turn were evidently 
derived from Protoblattoid ancestors. The Blattids, Mantids 
and Isoptera are the nearest living representatives of these 
Protoblattoid ancestors, and of these the Isoptera are in some 
respects the nearest living representatives of the Protoblattoid 
forms giving rise to the Protorthopteroid ancestors of the Gryllo- 
blattids, Dermaptera and Phasmids, so that we would expect to 
find among the Isoptera some types of head capsule suggesting 
the prototypes of the Dermapteroid head characteristic of the 
Grylloblattids, Dermaptera and Phasmids, and such is indeed 
the case. The resemblance, however, is more striking when one 
compares a Grylloid head, rather than the Grylloblattoid type, 
with a typical Isopterous head, since the head-contour, relation 
of the eyes, antennae, bases of the mandibles, etc., are more 
nearly alike in the Grylloids and Isoptera, than is the case in the 
Grylloblattoids and most Isoptera. The thoracic sclerites of 
the Grylloblattoids and other Orthopteroids are very like those 
of the Isoptera, and the evidence from this source would lend 
support to that of the head capsule in indicating that the Isoptera 
are very like the Protoblattoid ancestors of the Orthopteroid 
group of insects. 
While the head of such Blattids as Cryptocercus is rather 
suggestive of the precursor of the Orthopteran type of head, and 
the head capsule of such primitive Mantids as Eremiaphila 
exhibit certain features likewise suggestive of the starting point 
