106 



ARTHROPOD A. 



These insects are found commonly in damp places and on the 

 surface of pools. Desoria nivalis lives on the glaciers of the Alps, 

 the ice being sometimes blackened by its numbers. Templetonia 

 crystallina is said to do great mischief to the gutta-percha pro- 

 tecting the underground telegraph-wires of London. 



This order was separated from the following, with which it had 

 been included, by Sir J. Lubbock, who, however, does not regard 

 them as true insects in the " strictest sense." They are said to 

 be primitive, not degraded, forms of the original insect stock. 

 They are sometimes associated with the Neuroptera or with the 

 Orthoptera. Gerstaecker places them with the latter as a " tribe" 

 between Thripidae and the "true" Neuroptera; Glaus as a sub- 

 order, also of Orthoptera, before Forficulidas ; Schrnarda as an 

 order between Hemiptera and Orthoptera. It is the first order 

 of insects, including Thysanura, according to Von Hayek (1879). 



Smynthuridee. Templetonia. Desoria. 



Smynthurus. Orchesella. 



Papirius. Lipuridte. 



Degeeriidce. Poduridce. 



Lepidocyrtus. Podura. Anuridida. 



jria. Achorutes. Anurida. 



Order II. THYSANURA. 



Thorax of three, abdomen of ten segments ; the latter terminated 

 by setiforin appendages. Antennas long, many-jointed. Wing- 

 less. No metamorphosis. 



The mouth is more distinctly mandibulate. The abdomen be- 

 neath is furnished with groups of stiff hairs or with cylindrical 

 appendages. The females have an ovipositor. lapyx and Cam- 

 podea have no eyes ; the former has its caudal appendages (cerci) 

 modified into a pair of horny forceps. The nerve-centres are re- 

 duced to two ventral ganglia (Glaus). 



Unlike the preceding, these insects are found in dry warm places. 

 They are frequently clothed with hairs or with scales. Machilis 

 wiaritima is common on rocks by the sea. Campodea is sup- 

 posed to be " the representative of a form from which many other 

 groups have been derived." Lepisma saccharina is frequently 

 found among sugar. 



lapygidce. Lepismidce. 



Campodea. lapyx. Lepisma. 



Nicoletia. Machilis. 



