EPHEMERIDA. 



The mayflies are not well represented in California. The nymphs are 

 aquatic Their venation shows perhaps the largest number of veins found 

 among insects. In this and the following order the wings are rigidly at- 

 tached to the wing root and the musculation of the thorax is different from 

 that of preceeding orders. 



EPHEMERID/E. 



Ameletus exquisitus — Siphlurus. 

 Baetisca obesa Say. 

 Beetis obesa — Baetisca. 

 Callibaetis californicus Banks. 



hageni — tessel latus. 



])ictus — undulatus. 



tessellatus Hag. 



Fig-uie Z49 Venation of a mayfly 



undulatus Pict. 

 Heptagenia nitidus Eat. 

 Iron nitidus — Heptagenia. 

 Leptcphlebia rufivenosus Eat. 

 Siphlurus dissitus Eat. 



exquisitus Eat. 



330 



