LITERATURE CONSULTED. 



In working upon the order Collembola, one is confronted 

 at the very outset by a paucity of American hterature on the 

 subject. Excepting for Sir John Lubbock's Notes and Mono- 

 graph on the Tliysanura, the latest of which has passed its first 

 twenty years and is therefore sHghtly out of date, there is com- 

 paratively little in the English language to guide the systematic 

 student. Dr. Folsom and Miss Claypole have taken up one or 

 two species embryologically ; and Say, Packard, Ryder, Mac- 

 Gillivray and Harvey have described not a few new American 

 species. In case of Say and Packard no figures accompany the 

 descriptions, or at best, very useless ones in a few cases. Pack- 

 ard's species seem not unlikely to stand good, though most of 

 them need re-description. Some of this has been already done 

 by MacGillivray. 



To TuUberg, and more especially to Schott, must we look 

 for scientific treatises upon the order — works which present the 

 real microscopic characters of furcula and claws, so necessary in 

 determining the species. To the English-taught student the dif- 

 ficulty of pursuing ideas through the French, the German and 

 the Latin, the Italian, the Scandinavian tongues and the Bohemi- 

 an, often at second-hand by necessity, is not one to be considered 

 lightly. Yet, for all the lingual difficulties, I am very grate- 

 ful to Professor H. F. Nachtrieb, who has procured for me the 

 greater part of the standard literature upon the subject. With- 

 out this aid, much of my work would have been impossible 



There was need of a survey of the order which should do 

 more than merely list species. Working keys of American spec- 

 ies, accompanied by figures of the important features, and by de- 

 scriptions in English, regardless of whether a species is newly 

 described or not ; in short, a practical help to American students 

 has been the aim in this work. 



