138 THE ENTOMOLOGIST. 



number of the ' Enloraologist's Monthly Magazine' there is 

 an account of the metamorphosis of Stauropus fagi., by Mr. 

 Birchall. He had two opportunities of watching the 

 moulting of the larva, and describes the legs as being drawn 

 out of the old skin after the manner of crustaceans ; and not, 

 as I said, doubled up at the sides of the body, from which 

 position they could not be extricated until the skin had been 

 pushed back a considerable way. What Mr. Birchall says 

 about one of his larvae not renewing a lost joint at subsequent 

 moultings must be conclusive, for if the skin were cast in the 

 way I described the larva would surely have been provided 

 with an entire limb at the next moult. At the same time I 

 acknowledge it is difficult to divest my memory of what I 

 undoubtedly thought I saw, and which must have been an 

 " error of observation." When I sent my paper to the 

 ' Entomologist' (Entom. ix. 269) I was not aware that what I 

 depicted was new to those who had had opportunities of 

 watching Fagi.) although it was both new and surprising to 

 myself; and on reflection it seemed probable that an insect 

 which was unique in its form should be unique in its habits. 

 It would be interesting to know whether, theoretically, it 

 would not be consistent for the legs to be produced from 

 under the skin of the body, and not from within the old pairs, 

 for this reason : when the larva changes to pupa it always 

 rejects such parts as would be superfluous in the making of 

 the future moth, such as the prolegs, the apparatus for 

 biting, &c. (1 only speak of such parts as are essential to the 

 existence of the larva, not the accessories, — as hairs, &c.) 

 Now the three pairs of thoracic legs are required for the 

 insect in its perfect state ; and if they were packed away 

 under the skin, in the way I described, when this skin is 

 finally cast off by the pupa, the new pairs would be retained 

 within the case, weak and lender, and deferring their 

 development till the other parts were matured against the 

 emergence of the moth. Taking the other view, the legs 

 ought either to be thrown aside altogether when the larva 

 makes its last change, or else they should be drawn out of 

 the old skins, as on previous occasions, and be external to 

 the pupa, requiring thus a casing for themselves, more after 

 the lashion of Coleoptera. Although all Lepidopterous larv;B 

 bear but lillle likeness in form, and none in habit, to the 



