182 INSECTS 



to be recognised as an Order of Insects. The term was, how- 

 ever, revived hj Haeckel and Balfoin- several jeais since, and 

 applied quite properly to the Insects we have in view. Subse- 

 quently Packard and Brauer, recognising the claims of these 

 Insects to an isolated position, proposed for them the names 

 Synaptera and Apterygogenea, and I'ackard has also used the 

 term Cinura. There is, however, clearly an advantage in 

 retaining the termination " ptera " for each of the Orders of 

 Insects ; and as the fact that " Aptera " of Linnaeus included 

 many Insects is not a sufficient reason for refusing to apply the 

 term to a portion of the forms he used it for, we may, it is clear, 

 make use of the Linnaean name with propriety, it being explicitly 

 stated that the Order does not include by any means all the 

 apterous forms of Insects. 



The Order includes two sub-orders, viz. (1) Thysanura, in 

 which the hind body (abdomen) is composed of ten segments, and 

 there is no ventral tul)e on its first segment ; and (2) CoUenibola, 

 in which the hind body consists of not more than six segments, 

 the first of which is furnished beneath with a peculiar tube 

 or papilla. 



Thysanura, 



Our knowledge of this important sub -order has been re- 

 cently much increased by the works of Grassi^ and Oudemans.^ 

 Very little is known, however, of the extra -European forms, 

 there Ijeing great difficulties in the way of collecting and pre- 

 serving specimens of these Insects in such a way as to render 

 them available for study and accurate comparison. G-rassi and 

 Eovelli' recognise foiu- families among the few European species of 

 Thysanm-a, viz. Campodeidae, Japygidae, Machilidae, Lepismidae. 

 Campodeidae is perhaps limited to a single species, only one 

 liaving been satisfactorily established, though several descriptions 

 have been made of what are supposed to be other species. 



This Insect {Camjjodea stcqyhylinus) is, so far as external form 

 goes, well known, from its having been figured in many works 

 on natiu'al history on account of its having been supposed to be 



1 Mem. Ace. Lincei Ecnna (4), iv. 1888, p. 543, etc., and other preceding memoirs 

 mentioned therein. 



2 Bijdr. DierkvMdc, xvi. 1888, pp. 147-227. 

 ' Natural Sicil, ix. 1889, pp. 25, etc. 



