THYSANURA. 



In Great Britain this order is miicli less numerously 

 represented, both in species and in individuals, than 

 the CoLLEMBOLA. Indeed, I am only acquainted with 

 four British species, belonging to three, if not four 

 different genera. The Thysanura fall into two well- 

 marked divisions, represented by the LejpismidcB on the 

 one hand, the lapygidce and Nicoletiadoe on the other. 

 The former are clothed with scales, the latter with 

 hairs only. The LejnsmidcB appear to prefer dry and 

 warm or even hot localities, while the Collembola 

 frequent damp places, and apparently are most 

 numerous in the temperate regions of the earth. 



General Organization. 



The body consists of the head, three thoracic and 

 ten well-marked abdominal segments. The LGpismida^. 

 are covered with scales, which, however, are altogether 

 wanting in Nicoletla, Campodea, and lapyx. The 

 head is distinct, sometimes more or less covered by 

 the thorax. The eyes are large, compound, and 

 contiguous, in MacMlis ; small and far apart in 

 Lepisma ; larpyx has no eyes, and the same is the case, 

 according to Gervais, with Nicoletia and Campodea. 

 Westwood also is of the same opinion as regards 

 Campodea, in which genus, moreover, neither Meinert 

 nor I have been able to discover any eyes. Nicolet, 

 on the contrary, describes seven ocelli on each side of 

 the head in Nicoletia, and six in Campodea. 



