94 Proceedings of the Biological Society of Washington. 



(0.108 mm. + 0.112 mm.). Segments distinctly imbricated but without 

 secondary sensoria. Cornicles 0.24 mm. long and very distinctly im- 

 bricated, no distal flange present. Cauda about 0.128 mm. 



Color brown with the appendages black or very dark. Abdomen with 

 small black lateral spots which become large patches toward the thorax. 

 Caudad of the cornicles a large black patch is present which more or less 

 connects with a transverse black area on the caudal abdominal segments. 



Table of Measurements of Stem-mothers. 



Apterous Viviparous Female. 



Apterous forms occur throughout the summer in all generations. They 

 vary considerably in color from a brown to a pale yellowish white. The 

 first generation after the stem-mother matures about the second week in 

 May. 



Color brown or cream, some specimens apparently being all of the one 

 color and other specimens distinctly the other color. Legs and appendages 

 dusky or black. Black markings somewhat similar to those of the stem- 

 mother though not so prominently indicated on the sides. 



Length from vertex to tip of cauda, 1.76 mm. Width of abdomen, 1.04 

 mm. Antennae with the following measurements: Segment I, 0.064 



