CHAPTER I. 



ON THE CLASSIFICATION OF THE COLLEMBOLA AND 

 THYSANUEA. 



LiNN^us placed his genera Lepisma and Poclura 

 immediately after tlie Diptera, and at tlie head of the 

 Aptera, followed by Termes, Pediculus, Pidex, Acarus, 

 Phalangium, Aranea, Scorpio, Cancer, Monoculus, Onis- 

 cus, Scolopencha, and Julus, in the above order. 



The system adopted by Geoffrey was very similar. 

 He classed Poclura and Lejnsma, however, between 

 Pediculus and Acarus. 



Fabricius, on the contrary, on account of the struc- 

 ture of their mouths, united them with the Neuroptera, 

 in his order Synistata ; and in this view he was followed 

 by Blainville. 



The order Thysanura was established in 1796 by 

 Latreille, who placed it between Pulex and the Paea- 

 siTA. In the 'Considerations Generales' (1810), he 

 arranged it with the Myeiapoda and Paeasita among 

 the Aeachnida. In 1829, however, he regarded it 

 as the second order of Insects, placing it between 

 the Myeiapoda and the Paeasita. 



Lamarck, in his ' Animaux sans Yertebres,' adopted 

 the group Thysanuea, which he united with the Myria- 

 pods to form his Arachnicles Grustaceennes, constituting 

 the first section of his Arachnicles antennees-tracheales. 

 He even regarded the Thysanuea as more nearly allied 

 to the Crustacea than to the Insecta ; they are, he 

 said, " assurement point des Crustaces et encore moins 

 des Insectes." In separating them thus widely from the 



