INTRODUCTION. 



The Oollembola and Thysanuea, which form the sub- 

 ject of the present work, have hitherto been but little 

 studied in this country. Yet if a fallen bough be ex- 

 amined, a heap of moss shaken over a pocket-handker- 

 chief, or any long herbage swept with a hand-net, the 

 naturalist will not fail to find, together with numerous 

 beetles, flies, and other insects, certain delicate, hexa- 

 pod, active little creatures ; the majority of which will 

 endeavour to escape not only running with agility, but 

 also springing with considerable force, by means of a 

 sub-abdominal, forked organ, which, commencing near 

 the posterior end of the body, reaches forward, in most 

 cases, almost as far as the thorax. These constitute 

 the Linngean genus Podura, or Springtail ; subsequently 

 combined by Latreille with Lejnsma, and elevated 

 to the rank of an order under the name Thysanuea ; 

 but which, for reasons to be given presently, I have 

 again proposed to separate from the Lepismidce, and to 

 call CoLLEMBOLA, leaving Latreille's name Thysanuea 

 for the other portion of his group. 



Both the Thysanuea and the Collembola frequent 

 dark places ; but while the former prefer dry walls, 

 heaps of stones, or warm rooms — in short, warm and 

 dry places — the latter, with few exceptions, can only 

 live in moist situations, and suffer little from cold. 



Owing to their very general intolerance of light, we 

 know little as yet with reference to the habits of the 



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