1930 ] An Unusual Nest of Pogonomyrmex 65 
material received from Professor Shapley a very interesting 
series of pseudogynes was noted. 3 Since this series may be 
of significance in tracing the evolution of the wingless 
worker from the winged form, this description is offered. 
The typical female of P. calif ornicus Buckley is rather a 
large form (Fig. 1, A) about 8-9 mm. in length. It is 
much larger than the workers and pseudogynes, the dif- 
ference in size being most noticeable in the thorax and 
gaster. The thorax is of the typical Myrmicine type, being 
characterized by the presence of a large parascutellar 
region on either side of the mesonotum and by the absence 
of a distinct metathoracic spiracle. In the mesonotum the 
prescutum is fused with the scutum. The notauli are absent 
and the parapsidal furrows extend but a short distance 
forward from the transcutual suture. The lateral and ster- 
nal sclerites of the mesothorax are fused and modified so 
as to make their identification rather difficult. In the 
mesopleuron the epimeron persists as a narrow region bor- 
dering the postero-dorsal margin of the episternum. The 
episternum is secondly divided into an upper (anepi- 
sternum) and lower (katepisternum) plate. The meta- 
notum is reduced to a transverse plate and the metapleuron 
is almost indistinguishably fused with the propodeum. 
The modifications noted in the series selected for study 
are as follows. Fig. B is a lateral view of one of the 
larger winged pseudogynes. In this form fusion of the 
sclerites in the notal region has taken place although the 
mesonotal region is still enlarged, while the mesopleural 
region is practically unchanged except for a reduction in 
size. Vestigial wings and poorly developed tegulse are 
present. The metanotum persists as a transverse plate 
almost indistinguishably fused with the mesonotum and 
propodeum. In the form next to the true worker (Fig. C) 
fusion of the pleural region as well as the notal region 
has taken place, yet the pronotum is still separated from 
the enlarged mesonotum, the promesontal suture persisting 
in its entirety. In pseudogynes similar to this one vestigial 
3 Shapley considered these forms to be pterergates, but a comparison 
of a large number with the typical worker shows them to be 
pseudogynes. 
