l82 ENTOMOLOGICAL NEWS. [June, 



i68 hours for L. pulchellcL) these structures have not yet begun 

 to appear. The larvae of G. exilis thus leave the ^^'g in a less 

 developed condition than do those of L. pulchella, as is also 

 shown by the facts that food-yolk is still present in considerable 

 quantity in the mid-gut of exilis, whereas none is to be seen in 

 any part of the body o{ pulchella, and that, as a probable result 

 of the foregoing, the mid-gut epithelium oi pulchella is much 

 thicker than that of exilis. 



Moreover, neither of these species show any trace of tracheae, 

 blood vessels or reproductive organs, although tracheae are stated 

 and figured by Packard* to occur in embryos of Diplax, whose 

 age, however, is not given, and they exist in larva of Mesothemis 

 simplicicollis at sixteen days after oviposition and possibly earlier. 



The form of labium characteristic for the subfamily to which 

 the species belongs, is already present in the youngest larvae of 

 these two species, which also agree in possessing chitinous hairs 

 on the dorsal side of the body, arranged in a bilaterally-symmet- 

 rical manner. 



It is with a sad satisfaction that I acknowledge the aid and 

 advice given by the late Professor John A. Ryder during a con- 

 siderable part of these studies. 



SAWDUST FOR STEAMING. 



By B. J. B. Lembert. 

 How I came to use it would be too long a story to tell, but 

 give it, hoping others will be benefited, as much as I have been. 

 Mr. Wm. H. Edwards kindly furnished me with a description of 

 his method of steaming insects; it superseded the use of sand 

 steaming with me, but was not quite the thing for the mid and 

 high Sierras; it required too much watching, and the thorax of 

 the insects offered too much resistance to the passage of the pins 

 through them. One day I filled an open tin dish with dampened 

 sawdust, buried my papers with butterflies in them, in the saw- 

 dust, left them there forty-eight hours, and to my surprise the 

 insects were pinned and spread with an ease I had never as yet 

 experienced. I then tried to improve the method. I procured 

 a tin-box six inches broad, eight inches long and three inches 



* Proc. Bost. Soc. Nat. Hist, xi, pp. 365-372, 1868. 



