624. CAROLINE B. THOMPSON AND THOMAS E. SNYDER 
Internal anatomy. The brain (fig. 18) has a slightly greater 
bulk than in the worker, although the mushroom bodies are 
smaller. The optic lobes and the correlated compound eyes 
are both a little larger in this soldier than in its worker, a rather 
unusual occurrence. The lateral ocelli, though very small, are 
clearly visible, recalling the lateral ocelli of the soldier of Kalo- 
termes. The frontal gland is large, glandular, and functional. 
The reproductive system. In the male (fig. 38) all of the repro- 
ductive organs are present and fully fused, but the size of the 
organs indicates that their growth was arrested before develop- 
ment was complete, so that the male soldier of P. simplex is 
non-functional or sterile. 
The female reproductive system (figs. 18, 36) is considerably 
larger in the soldier than in the worker, but, like that of the 
worker, is evidently non-functional or sterile, although a certain 
degree of development has been attained. The ovaries contain 
ova which have begun to enlarge, the oviducts and vaginal duct 
are fused, but are narrow and without a lumen, the colleterial 
gland is large, but the seminal receptacle is small and vestigial. 
It is worthy of note that in young colorless soldiers with round 
heads the size of the ovaries and the contained ova is greater 
than in adult soldiers, showing that the retrogression of these 
sex organs does not begin until the soldier is almost adult. On 
first examining stained whole mounts of these young soldiers the 
writer was almost convinced that they were fertile, but the 
explanation may be found in the fact that this species of Pro- 
rhinotermes, and perhaps also the genus, although one of the 
higher termites, has many primitive characters which link it 
to the lower termites. The continuation of the period of growth 
of the soldier sex organs almost to the adult phase, together with 
the complete fusion of the embryonic fundaments in both sexes 
of the two sterile castes; the presence of ocelli in all castes, even 
in the soldier, as in the Kalotermitidae, and especially the pres- 
ence in the worker of a median bilobed ocellus in the place of the 
coenogenetic frontal gland, all contribute evidence for this view. 
