NORTH AMERICAN APTERYGOGENEA. 191 



joints are thicker than the others; the third is somewhat 

 longer than each of the following ones. Their color is 

 pale brownish violet. 



The labial palpi are three-jointed, and have the basal 

 joint somewhat longer than the following one. The ter- 

 minal joint is thicker than the others and irregularly- 

 triangular in form. They are uncolored. 



The thoracic tergits are shield-shaped and broader than 

 the abdominal tergits. Their ground -color is yellowish 

 white, and they are covered with dark brown scales, 

 which in alcoholic specimens remain only on the sides of 

 the tergits. On the abdomen almost all the scales are 

 fallen off, exposing a reddish violet ground -color. In 

 several specimens acute -angled areas, surrounded by 

 light lines, can be observed on the abdominal tergits. 

 When the animal is looked upon from above, the telson 

 seems to be widely triangular with the point slightly pro- 

 duced. When cut off, it appears to be such as the draw- 

 ing shows. The chitinous hooks, mentioned in the diag- 

 nosis, which in entire specimens are difficult to discern, 

 appear most distinctly on the segment, when cut off. 

 The cerci are distinctly annulated with reddish brown 

 and white. At the bases of the organs the rings are 

 smaller and increase in extent towards the points. The 

 joints towards the points of the antenna? become longer 

 and swollen. For the same reason that was mentioned 

 concerning the antennae, I cannot decide the length of 

 the cerci. Probably they are longer than the body. 

 The extremities are annulated with yellow and brown. 

 The cuticular figures are anchor-like and lie scattered on 

 a bottom quite plain. The scales are brown, and, there- 

 fore, the insect when alive probably bears this color. 

 The drawing belonging to this description represents al- 

 coholic individuals. I have thought fit to give a colored 



