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XXVII. Notes on the Thysanura. By John Lubbock, F.B.S., fr 
Part I. Smynthubid 
Read February 6th, 1862. 
1HE small but interesting group of animals to which 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 Fabricius 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 tliem 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 Lepismidas and Podurida?, together with the Pediculida- 
and Nirmida3, 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 with the Myria- 
pods : — " Par la masse de leurs caracteres, les Thysanoures appartiennent a la classe des 
Insectes. La composition du thorax, des organes de la locomotion, et de la bouche, Pin- 
diquent suffisamment. A l'egard meme de ces dernieres parties, et surtout de l'oviducte 
exterieur du plus grand nombre de femelles, les Thysanoures ont la plus grande affinite 
avec divers Orthopteres. Mais sous d'autres considerations, com m e l'absence de meta- 
morphoses, 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 l'ordre des Thysanoures : mais il nous semble, 
par son extreme concision, un peu trop vague; et aussi 
le signalerons ainsi : point de metamorphoses, ni de stigmates apparents; corps gene- 
ralement recouvert de petites ecailles, avec l'abdomen termine' par trois filets ou par 
une queue fourchue, servant a sauter." Of these four characters, only one is general to 
the whole group, as Smgnthurus, Fetrobius, and (according to Kicolet) Podura have 
spiracles; Smynthurus, Achorutes, Podura, Isotoma, and some other genera have no 
scales ; while, finally, in the Lipuridae the spring is absent or rudimentary, so that the 
power of jumping is entirely lost. Finally, Cams, in his useful work, ' Bibliotheca Zoo- 
logical places the Thysanura among the Orthoptera. 
For the present I will offer no opinion of my own as to the position and affinities 
d'ecarter tout embar 
