15 
1935 ] Structure of the Pretarsus 
the basipulvilli bear setae. The unguitractor and claws are 
not distinctive. 
The similarity of the claw-segment of Ithone with that of 
the Blattids is evident and perhaps significant, for this in- 
sect is considered to be the most primitive of the Plannipen- 
nia. Comparison of Figs. 17, 18 and 19 illustrates why 
Ithone may be considered as annectant between Corydalis 
and Mantispa. 
Mantispidae — Mantispa brunnea Say (Fig. 19) 
The pretarsus of Mantispa is provided with a complicated 
type of arolium which has probably developed from a simple 
pad such as found in Ithone. Two fleshy lobes are sup- 
ported by lightly sclerotized areas, indicated by broken 
lines, and at the base, posteriorly, are two ovoid sclerites 
also serving as supports. There is evidently no planta, a 
condition consistent with the light sclerotization of the 
planta in Ithone. At present it is impossible to interpret 
the significance of these various parts in Mantispa but it is 
hoped that other specimens of Neuroptera will make it 
possible to find homologies with the structures of higher 
insects. The basipulvilli are large and extend laterally a 
short distance along the membranes. The claws are broad 
and pectinate; the unguitractor differs considerably in out- 
line from that of Corydalis or Ithone and bears a median 
ridge. It will be noted that the claw-segment of Mantispa 
is not comparable to that of Corydalis in any of its features 
and, in fact, the divergency of these two types is greater 
than any variations found in other orders, a condition which 
emphasizes the fact that the Neuroptera are known to be 
a highly diversified group. 
Order Mecoptera 
Panorpa rufescens Rambur (Fig. 20) 
The unguitractor is oval and bears a conspicuous median 
ridge such as is found in Mantispa ; the claws are pectinate. 
A rod-like planta extends between the bases of the claws 
and the basipulvilli. The arolium is simple and is supported 
by a curved structure (cm) which is probably the same as 
the camera of Hymenoptera. 
