74 Cincinnati Society of Natural History. 



Accordino- to Mr. Riley iu Clisiocampa americana, Platysamia 

 cecropia, Callosamia promethea, Telea polyphemus and Antherce 

 yamamai there are five stages; whilst in Anisopteryx vernata, Anisota 

 rubicunda and Paphia gly cerium there arc only four; and I believe 

 that Mr. Healy records the same number in the Tineid moth Gracil- 

 laria syringella. According to my own observations, there are in the 

 Tineid moths of the genera Antispila and Aspiclisca only two larval 

 stages, in Tischeria five, and as more fully detailed hereafter there 

 are seven in Lithocolletis. 



The number of larval stages among Lepidoptera therefore ranges 

 from one to seven, or even ten if the statement as to Arctia caja is 

 correct. 



I have alluded to the apparent suddenness of the metamorphoses of 

 Lepidoptera. In fact the changes are not so sudden as they appear to 

 be. Concealed within the integument changes have been gradually 

 accomplished, which only became apparent on the sloughing off of the 

 old skin, and these changes have been brought about simply by the 

 rapid growth of some parts, and the arrest of growth or absorption of 

 other parts. They diff'er from the changes which are observed in the 

 development of a vertebrate, chiefly in their periodicity, and in the 

 casting of the skin, whereby they are made evident: but they are as 

 much the result of growth and absorption as are the metamorphoses of 

 a froo". That which makes the metamorphoses of an insect peculiarly 

 striking, is its apparent suddenness, and its periodicity, especially the 

 former, accompanied as it is by a moult of the integument, whereby 

 a being is disclosed often so widely dift'erent from the lorm in which it 

 had just previously appeared. 



Various hypotheses have been suggested to account for the phenome- 

 non of a sudden and complete cast of the integument. It has been 

 suggested that the skin of the larva ceases to grow, and becoming too 

 small for the contained animal, it is cast ofl", but no explauation is 

 given by this hypothesis why the entire skin ceases all at once to grow, 

 while the growth of the animal continues; nor wh'y, nor how, the animal 

 becomes separated from its skin ; and this explanation leaves entirely out 

 of view the periodicity which we shall see characterizes the phenomenon, 

 and its relation to temperature, and quantity of food consumed. Buvmeis- 

 ter in his manual suggests that the skin becomes too (\v\. and is there- 

 fore cast off: but he saw himself that such an explanation wou.d explain 

 nothing, and was not at ail applicable to larva? living in water; and 

 besides it is open to all of the objections urged against the preced- 

 ing hypotheses. The distinguished author of the " Guide to the Study 



