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PART III. 



ON THE CLASS OF APTEROUS INSECTS. 



CHAP. I. 



ON THE APTERA GENERALLT, 



(3 16.) The second, or sub-typical, class of annulose 

 animals is the Aptera of Aristotle; which is connected to 

 the Ptilota of the same immortal zoologist by the order 

 of Diptera. The general reader will readily understand 

 this class, on being told it contains the different families 

 of the spiders, centipedes, scorpions, crabs, and other 

 wingless groups, together with the flies ; which, as stand- 

 ing at the confines of the whole, connect the apterous 

 orders with such as are provided with four wings. 



(317.) Our definition of this group, in its primary 

 or typical characters, is in accordance with those of 

 Aristotle, Linnseus, and Fabricius, — three names quite 

 sufficient, if science reposed upon mere authority, to 

 counterbalance all those of modern times who hold op- 

 posite opinions. As we have simply defined an insect 

 to be a creature which moves on the earth by means of 

 jointed legs, so do we comprehend under the name of 

 Aptera, all such as are either destitute of wings in every 

 stage of their existence, or which have, in their adult 

 state, only two. Like the typical insects, they are all 

 more or less subject to metamorphosis, but in different 

 ways ; for this change is a primary character of the 

 typical Annulosa, and is even extended to one of the 

 aberrant classes, — namely, the Cirrhipedes, or barnacles. 



(318.) Before we enter further into this subject, it 

 A a 4 



