502 CAROLINE BURLING THOMPSON 



opaque, slender, though rather short in comparison with the 

 first-form nymphs of other genera — a characteristic of this genus. 

 In stained whole mounts (fig. 1, a) the thickened and greatly 

 convoluted embryonic tissue of the future wings, w.p., is clearly 

 seen, the veins and tracheae in process of formation. The meso- 

 and metathoracic tergites are narrow from side to side as in the 

 adult. The notable features of the legs are the five tarsal seg- 

 ments, a primitive character, and the pulvillus or onychium 



b 



Fig. 2 Termopsis angusticoUis. a, mature nymph of the first form, lateral 

 view of head; b, immature nymph of the first form, lateral view of head. Spencer 

 oc. 6, obj. 32 mm., stage level, reduced one-third. 



between the claws. The lateral tibial spines (fig. 3, 6) are almost 

 as large as in the adult, and are variable in number, from five to 

 one. Female nymphs are clearly recognized from males by the 

 larger seventh abdominal segment which, on the ventral surface, 

 practically covers the eighth. Styles or genital appendices are 

 present on the ninth segment in both sexes. The anal cerci 

 consist of five segments. 



Other external points of difference between the mature and 

 immature njanphs, besides the differences in eyes, wing pads, and 



