OBTHOPTEBA. 215 



is technically called semi-complete that is to say, the 

 changes in external form, which they undergo in their 

 transition from one state to another, are only half so 

 considerable as those which take place in some other 

 instances the Lepidoptera for example. In fact, it 

 is difficult, in many instances, from inspecting an in- 

 dividual to say what stage of its progress it has 

 reached. The final state, however, may usually be 

 determined by the full development of the wings and 

 tegmina ; these members exist in the pupa only in 

 a rudimentary condition. The pupa is never quiescent, 

 but moves about and takes food. Not only do the 

 larva and pupa resemble the perfect insect in exter- 

 nal appearance, but it is likewise found on dissection 

 that their internal organisation is similar. In the 

 penultimate and antepenultimate states, the sexes are 

 likewise distinct, and copulation sometimes takes 

 place, but it is improbable that this premature union 

 ever proves productive. The transformations in 

 question, therefore, must be considered as merely a 

 series of gradual approaches to perfection, none of 

 the transitions being marked by any decided change 

 of general form, the only consequences resulting from 

 ecdysis, or casting of the external crust, being in- 

 crease of size, slight development of certain parts, 

 and an aptitude to continue the species. 



This order is one of the least numerous in species. 

 But its poverty in this respect is in some measure 

 compensated for by the great amount of individuals 

 of the same species, the swarms of locusts, grass- 

 hoppers, and cockroaches, which sometimes congre- 



