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as yet described. He then made some remarks on the 
reproduction of lost parts, especially on the reparation of 
■wounded antennae. He showed that if an antenna is cut 
off, for example, in the middle, it never again recovers the 
normal number of segments, and he mentions the curious 
fact that among the species with longest antennae it is 
extremely rare to find a full-grown specimen in which these 
organs are perfect. It is also remarkable that the reproduced 
segments acquire an abnormal length. Thus, for instance, if 
a Tomocerus has the terminal and part of the third segment 
removed, the terminal segment is never reproduced, though 
the penultimate one acquires a greater length than in un- 
mutilated specimens. 
Sir John then described the internal anatomy of the 
Thysanura, alluding successively to the digestive, respira- 
tory, nervous, reproductive, and muscular systems. In 
opposition to Nicolet, he denied the existence of Malpighian 
vessels or of tracheae. The latter point is one of much 
interest, and the more so, perhaps, because, as Sir John 
pointed out, while the majority of the group has no well- 
developed system of tracheae, in Smynthurus, on the con- 
trary, they are easily visible. Sir John dwelt at considerable 
length on the arrangement of the muscles, especially de- 
scribing the mechanism of the spring and of the ventral 
tube. 
He then made some remarks on the classification of the 
Thysanura. He pointed out that the Lepismidse and 
Poduridae w r ere much less nearly allied than had hitherto 
been supposed ; and he considered that the Poduridae, 
Smynthuridae, and Lipuridse formed . a well-marked and 
distinct group, characterised specially by the presence of 
the gastric tube, to which he attributed greater classificatory 
importance than to the saltatory appendage. 
Finally, he expressed the opinion that this group, though 
nearly allied to the true Insects, differed more from the 
Coleoptera, Lepidoptera, and other typical orders of insects, 
than these groups do from one another. 
