214 



PTILOTA. 



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



In many of the wood-boring- 

 species of Lepidoptera (as, 

 for instance, the Goat-moth) 

 the abdominal segments of 

 the pupa are fm-nished with 

 transverse ridges of minute 

 hooks, which are ser^^ceable 

 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. 



Fig. 49, Pupa of an Ichneumon and 

 Callimome. 





Lateral view of the pupa of the goat-moth, lettered as Nos. 46, 47, and 48 ; and T 1, T2, ab-.. 

 T 3, being the three thoracic segments ; X X, two of the rows of hooks. 



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 tyjjical number of 

 segments, but in 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 



