CASTES OF TERMOPSIS 525 



DISCUSSION 



To review briefly the more significant facts stated in the pre- 

 ceding sections we find that the colonies of T. angusticollis 

 have commonly four stable types or castes of individuals, the first, 

 second, and third forms, fertile; and the soldier, wholly or almost 

 sterile, with occasional and rare deviations or variations from one 

 or all of the castes. We find, further, that each caste is a complex 

 of evidently correlated characters which, on the whole, are well 

 defined, although the range of variability in Termopsis is unusu- 

 ally great. 



The first form, with long wings or stubs, has, as a rule, the 

 highest type of structure, so that in general there is a gradation 

 of structure from the first form down through the other castes. 

 Examples of this are: the brain, the compound eyes, the frontal 

 gland (present only in the first form), the wings, the size of the 

 lateral tibial spines, the body pigment, the anal cerci. In fewer 

 cases there is gradation up from the first form, e.g., the size of the 

 head, of the testes, and of the soldier mandibles and legs. 



The genus Termopsis is remarkable for the retention of many 

 primitive characters, both in habits and in structure. Among 

 habits may be mentioned the activity of the old egg-laying queens; 

 the relatively strong powers of flight of the winged first forms in 

 comparison with other termites genera; the lack of a true nest 

 except for the galleries in wood; the frequent presence of several 

 parent first forms in a colony. 



The list of primitive structures is a long one. The great size; 

 the large number of antennal segments, twenty-six to twenty- 

 seven; the hypodermal plate that forms the non-glandular 

 frontal gland of the first form; the vestiges of the lateral ocelli; 

 the slightly reniform condition of the compound eyes of the first 

 form, especially in the nymphal phase; the incomplete humeral 

 suture of the wings; the primitive type of venation; the wing 

 vestiges of third form and soldier; the arrangement of the lateral 

 tibial spines on the three pairs of legs, similar to that of Archo- 

 termopsis; the five tarsal segments; the very slight post-adult 

 growth of the abdomen of the egg-laying queens ; the four enteric 

 caeca of all castes; the eight malpighian tubules of the digestive 



JOURNAL OF MOBPHOLOQT, VOL. 36, NO. 4 



