432 A New Species of Cicada, from the Cascade Mountains. 



in the central piece on each side. They are capable of being 

 moved in any manner, separate or together, as the insect wills, 

 the centre piece being always a fixture. The instrument is 

 highly polished, and it is difficult to imagine that it is made up 

 of distinct pieces, so admirably do they fit, and so rapidly is 

 the work performed. The handles, if I may so name them, of 

 these files, being composed of horn, afford a fixed and solid 

 attachment ifor the muscles, that cause the files to be pressed 

 closer and firmer to the centre-piece while in the act of 

 sawing. 



When the time arrived for depositing her eggs (about four- 

 teen days after the final change), the female selected a branch 

 from which the sap had commenced to dry up, or, in other 

 words, which would soon decay. I observed this mode of 

 selection more in the open forest, than during the insect's im- 

 prisonment. She first clasps the branch both sides with her 

 legs, and with the end of the file very carefully slits up the bark, 

 then placing the instrument longitudinally, files away, until she 



Tfest and Eggs of Cicada Oceidentalis, magnified. 



has obtained sufficient length and breadth. The small teeth of 

 the files are now used crosswise of this fissure, until a trench is 

 made in the soft pith. When large enough, slowly down the 

 groove in the centre of the instrument glides a small, pearly 

 egg, pointed at both ends, and so transparent, that the little 

 grub within is easily discernible. Gently she lays it within its 

 bed, and then drops a thin gummy material on it, to secure it 

 from moisture. This finished, she proceeds to deposit another, 

 and so on, until a sufficient number are produced to fill the 

 fissure; then over all she drags the everted bark. It is easy 

 to perceive where the cicada has been concealiug her brood, 

 by the elevations on the branch. In this manner she deposits 

 about seven hundred eggs, going from branch to branch, her 

 marvellous instinct teaching her to select the most suitable 

 wood for the purpose. The time occupied in constructing 

 each nest was from fifteen to twenty minutes. Her earthly 



