594 CAROLINE B. THOMPSON AND THOMAS E. SNYDER 
from Florida, in all of which the third form is present, and is of 
frequent occurrence in species of the first two genera. 
Comparative studies of the castes of Reticulitermes and 
Prorhinotermes form the subject matter of the present paper, 
and it will readily be seen that, although the elucidation of the 
third form is the chief end in view, it is necessary for comparison 
to describe or figure the various castes of each genus. 
Two morphological facts, which apply to all the termites here 
described, should be borne in mind: first, that, together with 
certain external characters, such as wings, there is a correlation 
in the size, structure, and degree of development of the brain, 
the eyes, and the sex organs; second, that, in general, in whatever 
castes are represented, there is a gradation in the size of these 
organs, from the first form down to the worker or soldier. 
One writer (T. E. 8.) is the discoverer of the third-form nymphs 
and adults, and is responsible for the collection of most of the 
material and for the biological data of this paper, the other 
writer (C. B. T.) is accountable for the morphological study, the 
drawings, and for a part of the Termopsis material. 
RETICULITERMES FLAVIPES KOLLAR 
This species is widely distributed throughout the eastern 
United States from Maine to the Florida Everglades. It is 
essentially a wood destroyer, but colonies may be found either 
in decaying wood or in the ground. Throughout the world, 
wherever they occur, the species of this genus are most destruc- 
tive to timber and the woodwork of buildings. 
The castes of R. flavipes are five in number, three of which 
are reproductive or fertile forms, while two are non-reproductive 
or sterile. The reproductive castes are: 1) the first form, with 
long wings at the time of swarming, and mere stubs, the ‘scales,’ 
after deiilation; 2) the second form, with short scaly wing vestiges; 
3) the third form, wingless, with creamy white abdomen. The 
sterile castes are: 4) the worker, wingless, with grayish abdomen, 
and, 5) the soldier, wingless, with elongated head. All of these 
castes are found in both the nymphal and adult conditions, © 
according to the season of the year. » In a normal colony in which 
