1 82 INSECTS 



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

 ever, revived by Haeckel and Balfour several years 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 Packard 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 tube on its first segment ; and (2) Collemhola, 

 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 being 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. Grassi and 

 Eovelli^ recognise four families among the few European species of 

 Thysanura, viz. Campodeidae, Japygidae, Machilidae, Lepismidae. 

 Campodeidae is perhaps limited to a single species, only one 

 having been satisfactorily established, though several descriptions 

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



This Insect (Campodea stapkylinus) is, so far as external form 

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

 on natural history on account of its having been supposed to be 



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

 mentioned therein. 



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

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



