232 



[March, 



In the December number 



legs were drawn out from the old shells precisely after tlie manner of a crab or 

 lobster, but with much greater ease, owing to the small amount of contraction at the 

 joints, a few seconds only been needed for the operation. The new legs on emergence 

 are semi-transparent and apparently soft, and are at once folded up against the fore- 

 part of the caterpillar, which then rests for a few minutes, for the purpose, I suppose, 

 of allowing the newly-developed legs to acquire colour and hardness by exposure to 

 the air ; in about five minutes they are unfolded, and the work of extricating the 

 body proceeds ; the swollen terminal segments offer no difficulty, the old skin 

 seeming to possess great elasticity. 



of Newman's Entomologist, pp. 269 — 272, 

 Mrs. Grolding Bird states that Staur opus fag i 

 has two sets of legs at one and the same time ; 

 that the two old pairs (why not three pairs ?) 

 are cast with the old skin of the body, and 

 that two new pairs are then found doubled up 

 against the sides of the larva. Mrs. Bird oifers 

 some elaborate speculations on the sudden 

 transfer of muscular power and connexion 

 with the body from the old legs to the new 

 ones ; but I think it is hardly necessary to 

 argue against a theory which, as it appears to 

 me, rests upon a mere error of observation, and 

 which, if true, would make the metamorphosis 

 of Stauropus fagi a solitary habit without a 

 parallel in creation. The hairs and spines of caterpillars are merely dermal appen- 

 dages, and lie on the surface of what is to be the new skin ; but the limbs and 

 other members are in all cases developed inside the old ones, and withdrawn from 

 theiti in moulting. Mrs. Bird has simply missed the critical moment of withdrawal, 

 and if she had carefully examined the supposed old legs, would have found merely 

 empty shells. 



One of my larvae had lost the whole of the second off fore-leg, except tlie coxa, 

 when it reached me, also nearly the whole of the caudal horn on the same side ; it 

 did not seem to suffer any inconvenience from these losses, and at none of the tliree 

 subsequent changes of skin which took place was there any renewal of the missing 

 members or increase in the length of the stumps ; although no instance of the re- 

 production of loet parts amongst the Lepidoptera has come under my notice, the 

 semi-crustaceous aspect of this caterpillar led me to look for, and almost to expect, 

 something of the sort. Had there been new legs packed away under the skin of the 

 body, as Mrs. Bird supposes, we might certainly have looked for a complete set to be 

 supplied. 



When the larva is at rest, the legs are doubled up in front like a carpenter's 

 rule, and the insect, especially when young, closely resembles in colour and outline 

 one of the twigs of beech with unopened buds on which it frequently stations itself. 

 {See Illustration.) When feeding the long legs are protruded, and the anal segments 

 being elevated, its likeness to a great eai'wig or Slaphylinus is very striking, and 

 probably may give it some security from the attack of enemies. Ichneumons may 

 fail- to recognize it as a Lepidoptera us larva,jind other foes may dread the anal 



