498 CAROLINE BURLING THOMPSON 



The second form of T. angusticollis (fig. 6) with very short wing 

 vestiges extending only to the first^ abdominal segment, and some 

 specimens with even shorter wing vestiges, is of infrequent occur- 

 rence. It is possible that this form has been overlooked by col- 

 lectors on account of its inconspicuousness and that it may be more 

 common than is now supposed. Among the many specimens of 

 reproductive adults collected from about fifty colonies in Pacific 

 Grove, Calif orinia, I have only six individuals of the caste, two of 

 which were taken for third forms until 1113^ attention was called to 

 their ver^' short wing vestiges by Dr. T. E. Snyder, and four 

 which were at first considered young first-form nymphs. 



The wingless third-form individuals have a wide range in size, 

 seen not only in the abdomen, which increases but slightly with 

 age, but also in the head and thorax. The body length of 3"oung 

 egg-laying females of my collection varies from 11 to 13 mm., and 

 the width of the head of both sexes ranges from 2.5 to 3.7 mm. 

 Older third-form females with shghtly enlarged abdomens measure 

 from 15 to 17 mm. long. A number of individuals closely resem- 

 bling the third form in structure, but with very minute wing 

 vestiges (fig. 8), have been found and will be referred to again. 



The soldiers have a still greater size range, the body length, 

 from tip of mandibles to the end of the last abdominal segment, 

 varying from 15 to 25 mm., and all sizes may be found in a single 

 colony. In a colony taken on May 12, 1919, a number of young 

 white soldiers, evidently just molted, were present. Examining 

 the material later, three of these young soldiers, one female and 

 two males, were found to have wing pads. The other young 

 soldiers of the same lot were normal. The histology of these 

 soldiers with wing vestiges will be described below. It will be 

 recalled that in the related genus Kalotermes soldiers with wing 

 vestiges are not uncommon, and occur in man^^ species. 



The soldiers with wing vestiges and the second- and third- 

 form individuals with minute wing vestiges are to be regarded as 

 evidences of the high degree of variability of this genus, especially 

 in the direction of the retention of primitive characters. 



2 The sternite, or the ventral part, of the first abdominal segment of termites 

 is not developed, so that the true second segment appears to be the first, when 

 viewed from the ventral surface, and for convenience will be so termed in this 

 paper. 



