8 



appreciative audience in the members of the Liverpool 

 Microscopical Society. 



The subject I have chosen to speak about in my address 

 to you this evening, is " The Study of the Structure of the 

 Head and Thorax of Lepidoptera " — a field of observation 

 of wide and varied character, much of which has been 

 entirely untrodden. I had hoped to have confined myself 

 to the wing structure alone, but the amount of original work 

 that was necessary was too large an undertaking for the 

 short time I have had for the preparation of the address, 

 and to-night I must be content to merely touch upon the 

 ground in the most superficial way. 



Lepidoptera have been classified as : — Insects with 

 four sealed wings, Mandibles absent in the image, very 

 rarely present in the pupa, first maxillae with galeae much 

 lengthened and grooved, forming when united a perfect 

 sucking tube, complete metamorphosis. The larvae are 

 eruciform (caterpillars), with three pairs of thoracic legs, 

 and two to five pairs of abdominal prolegs. The eggs are 

 of various shapes, some beautifully sculptured, others 

 shining smooth, like mother o' pearl ; the time of hatching 

 varies according to species, some producing young larvae in 

 a few days, others lying over the winter before the eggs 

 hatch. Experiments have been made which show that 

 cold retards and heat accelerates the hatching ; eggs that 

 have been frozen have kept for a long period without 

 affecting the larva. Unlike some other orders of insects, I 

 know of no instance of a lepidopteron being vivparous. 



The young larva on hatching is fully developed, and 

 has its body segmented ; these segments are observable 

 during the different transformations, but owing to the 

 segments sometimes being fused together, the division is 

 not always apparent. In the larval state certain segments 

 have spiracles, and others have not ; this system is fairly 

 constant throughout the whole order. The head is usually 

 spoken of as the first segment, although in reality it is 

 composed of several sclerites, fused together. Attached 



