214 1'TIJ.OTA. 



the abdomen, although in some it is stretched ont at length. 

 In many of the wood-boring 

 species of Lepidoptera (as, 

 for instance, the Goat-moth) 

 the abdominal segments of 

 the pupa are furnished with 

 transverse ridges of minute 

 hooks, which are serviceable 

 to the insect, when about to 

 assume the imago state, in 



working its way to the orifice of its burrow, the hooks, by 

 the alternate contraction of the abdominal rings, being em- 

 ployed as anchors in preventing the insect from falling back- 

 wards. 



There is a curious circumstance connected with the de- 

 velopement of the insect structure, especially interesting as 

 regards the pupa state of insects, which has hitherto re- 

 ceived but very little attention. In the larva state the 

 body is composed of the ordinary and typical number of 

 segments, but hi the perfect state some of the segments are 

 not to be found. The change, therefore, must take place at 

 the period of the insect's assuming the pupa state. Dr. 

 Ratzeburg, indeed, accounted for the loss of one of these 

 segments, by asserting that the head of the pupa of the bee 

 corresponds with the head and first segment of the body of 



