154 NATURAL HISTORY OF ARTHROPODS. 



northern Europe, especially Lapland. In Clo'e there are sometimes but two wings, 

 the hinder pair wanting; while the species of Coenis nevei- have any hind wings. 

 The most abnormal ephemerid is Oligoneuria, in which the wing-veins are very few, 

 and far apart, and the legs are imperfectly developed, and there are three caudal 

 threads. Allied to this is a Cuban form, Lachlania ahiormis, in which there are 

 but two caudal threads. 



A. S. Packaed, Je. 



Fig. 225. — PsoCTis. 



