486 Dr. Harry piMeham on the Larvae and 
Similar structures are found * on the prolegs of Teratoneura 
isabellae, and one of these is illustrated on a larger scale 
on Pl. XII, fig. 14. They consist of small diverticula of 
the cuticle, extensible by internal fluid pressure. We have 
discussed these structures with Dr. 'T. A. Chapman, F.R.S., 
who has given us much valuable information on the subject. 
In most Microlepidoptera there is on the prolegs a complete 
circle of hooks, whilst in most Macrolepidoptera half the 
circle has become atrophied. Dr. Chapman states that he 
formerly expressed the opinion that it was the outer half 
of the circle which had been preserved and the inner half 
lost. He now considers that the reverse is the case and 
that in those species in which but half the circle of hooks 
remains, it is the inner half which persists.. Now within 
this circle of hooks there is a kind of pad which can be 
protruded or withdrawn. This action gives to the hooks 
a rocking motion by which they engage and disengage 
with the surface on which the larva is progressing. There 
can be but little doubt that the papillae observed in many 
Lycaenid larvae are really developments of the centre 
of the extensible pad, and that they assist the larva by 
adhesive or tactile functions, or perhaps both. On this 
point see Farquharson’s account on pp. 352, ete. That this 
is almost certainly the correct interpretation of the develop- 
ment of the papilla is shown by text fig. 4, which is a section 
* Some of the detail of the original drawings has been lost in 
reproduction. Most of the figures will, however, bear examination 
with a low-power hand lens. 
a 
