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XXVII. Notes on the Thysanura. By John Lubbock, F.B.S., 8fc. 

 Part I. Smtnthurid^. 



Read February 6th, 1862. 



iHE small but interesting" group of animals to whicli Latreille gave the name of " Thy- 

 sanoura" has, by different systematists,' been placed in very different parts of the sub- 

 kingdom Annulosa. Without recording all the successive places which have been 

 assigned to these little creatures, I may mention that Pabi'icius classed them among his 

 Synistata, which correspond in great measure to our Neuroptera, — a view as to their 

 affinities which was also adopted by Blainville. Lamarck considered them to be allied 

 to the Arachnida rather than to the Insecta, while Cuvier placed them between the 

 Myriapoda and Parasita. Von Siebold does not adopt the order Thysanura, but con- 

 siders that the two families of Lepismidse and Poduridse, together with the Pediculidse 

 and Nirmidse, form the order Aptera, which he regards as the first among the true 

 Insects — the Myriapoda forming, in his system, part of the Crustacea. Latreille con- 

 sidered them as a separate order of Insects, connecting these latter Avith the Myria- 

 pods : — " Par la masse de leurs caracteres, les Thysanoiu'es appartiennent a la classe des 

 Insectes. La composition du thorax, des organes de la locomotion, et de la bouche, I'iu- 

 diquent suffisamment. A I'egard meme de ces dernieres parties, et surtout de I'oviducte 

 ext^rieur du plus grand nombre de femelles, les Thysanoures ont la plus grande afflnite 

 avec divers Orthopteres. Mais sous d'autres considerations, comme I'absence de meta- 

 naorphoses, les organes de la vision, les appendices abdominaux et les habitudes, ils se 

 rapprochent aussi des Myriapodes et des Arachnides. D'apres un tel melange de rap- 

 ports, il est naturel de conclure que ces animaux font la transition des Myriapodes aux 

 Insectes, et que vu leur plus grande ressemblance avec ceux-ci, ils doivent etre places a 

 leur tete. Point de transformations, abdomen termine par des soies, tel est, suivant le 

 docteur Leach, le caractere essentiel de I'ordre des Thysanoures : mais il nous semble, 

 par son extreme concision, un peu trop vague; et aussi d'ecarter tout embarras, nous 

 le signalerons ainsi : point de metamorphoses, ni de stigmates apparents ; corps gene- 

 ralement reconvert de petites ecailles, avec I'abdomen termini par trois filets ou par 

 une queue fourchue, servant a sauter." Of these four characters, only one is general to 

 the whole group, as Smynthurus, Petrohms, and (according to Nicolet) Podura have 

 spiracles; Smynthurus, Achorutes, Podura, Isotoma, and some other genera have no 

 scales ; while, finally, in the Lipurida3 the spring is absent or rudimentary, so that the 

 power of jumping is entirely lost. Finally, Cams, in his useful work, ' Bibliotheca Zoo- 

 logica,' places the Thysanura among the Orthoptera. 



For the present I will ofi'er no opinion of my own as to the position and affinities 



