LITERATURE CONSULTED. 



In working upon the order Collembola, one is confronted 

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

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

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

 twenty years and is therefore slightly out of date, there is com- 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 Tullberg, 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. 



