142 
Psyche 
[December 
Melophorus bagoti and that of the ninth in Pseudomyrma 
Icewensohni; in the male larva of Eciton (A.) schmitti there 
is none on the seventh and eighth and only a very faint trace 
on the ninth ; in Eusphinctus steinheili there is none at all. 
It is interesting to note here that these same structures 
also occur in other aculeate Hymenoptera. Three pairs of 
vestigial legs, two pairs of wing rudiments, and three pairs 
of vestigial gonopods (on the seventh, eighth, and ninth 
abdominal segments) are present in the larvae of the hornet, 
V espula (Dolichov espula) maculata (L.) ; of the yellow 
jackets, V espula (F.) maculifrons (R. du Buysson) and 
V. (F.) arenaria (Fabr.) ; of the wasp, Polistes pallipes 
LePeletier (Fig. 8) ; and of an undetermined mud dauber 
(Sphecidse). I have, however, been unable to find any such 
structures in the worker honeybee, in the drone honeybee, 
nor in an undetermined bumblebee. 
The leg vestiges in V espula arenaria (Fig. 7) are open 
transverse grooves, which fact of itself suggests a possible 
sensory function. Furthermore one of my sections shows a 
structure (Fig. 9) , which might be nervous, extending from 
the bottom of this groove to the hypodermis. A section of a 
gonopodal imaginal disc reveals in the overlying integument 
a small sensilliform structure (Fig. 6) . 
Four possible interpretations of these structures have 
occurred to me. (1) All three types are vestiges : vestigial 
legs on the three thoracic segments; vestigial abdominal 
legs (gonopods) on the seventh, eighth, and ninth abdominal 
segments ; and vestigial wing pads on mesothorax and 
metathorax. (2) All three types are rudiments of adult 
structures appearing prematurely in these holometabolous 
larvae. (3) The six pairs of ventral structures are vestiges, 
while the two pairs limited to the mesothorax and meta- 
thorax are prothetelous rudiments. (4) All are the results 
of purely developmental processes and limited to the cuticula 
at the points where the hypodermis first invaginates to form 
the imaginal buds. Personally I am inclined to prefer the 
third interpretation. 
