530 KNOWER. [Vol. XVI. 



development briefly, referring to the series of diagrams on 

 PL XXXII for the general characteristics necessary to an under- 

 standing of this special study. A complete series of figures 

 of the later stages will be published in the near future. 



The first traces of segmentation and appendages appear, 

 suddenly, a little later than the last stage described, where the 

 germ-band had become a ^/-shaped cap over the posterior end of 

 the yolk-mass (PI. XXXI, Fig. 29). At this stage the antennae 

 have just become evident as backward processes of the cephalic 

 lobes, post-oral in position. The first maxillary and first tho- 

 racic are more distinct than the other anterior segments, which 

 are however outlined. The " tail-piece " is long and unseg- 

 mented. The anterior segments through the first thoracic have 

 therefore arisen almost simultaneously. There are no macro- 

 somites described by Graber (8) and {9) for Stenobothrus and 

 other forms. 



Later embryos exhibit a progressive increase in the length 

 and complexity of the germ-band. 



When the hind end of the band has pushed forward along 

 the dorsal surface of the yolk almost to the anterior end of the 

 ^&S> three additional segments have been added. These are 

 the two posterior thoracic segments and the first abdominal, 

 and they are added successively from before back ; since I have 

 embryos in which the first thoracic is the last segment dis- 

 tinguishable, others with an indistinct second thoracic behind 

 this, and yet a third lot with three distinct thoracic and an 

 indistinct abdominal segment. In older embryos more ab- 

 dominal segments are added behind. A "tail-piece" of un- 

 specialized (ecto- and mesoderm) material is found at the end 

 of the band during this process, the abdominal segments being 

 successively differentiated from its anterior edge. {See final 

 section of this paper and filial plate) 



Graber's (9) beautiful figures of the development of the 

 Orthopteran, Stenobothrus, would serve fairly well, in most 

 respects, to illustrate the general features of the growth of the 

 germ-band of the Termite from a disc-like rudiment to an 

 elongated, segmented embryo at the period of " revolution." 

 This process was not observed by Graber in Stenobothrus. It 



