OF MANDIBULATA. 443 



solid parts which in so many cases afford support to the 

 muscles. It is clear that such a process must occasion a 

 crisis in the life of an Annulose animal incomparably more 

 decisive in its effects than what can be produced among 

 the Vertebrata, by merely being set free from an integu- 

 ment. All the marvellous, however, of ecdysis was with 

 the earlier naturalists comprehended in the change of form, 

 and consequently the shedding of the envelope only excited 

 attention where it regarded a few of the Amudosa. Hence 

 it "was- a great discovery of Linnreus that every Annulose 

 animal ought to be considered as subject to metamorpho- 

 sis. It may indeed have led to his more artificial notion 

 of every- externally articulated being having a nympha 

 state; but even this helped Fabricius to give, although with 

 a faulty nomenclature, a much more convenient division of 

 metamorphosis, than he could otherwise have devised. 



Ecdysis, by whickterm is signified generally every change 

 in the identity of the envelope of a living body, may either 

 be complete or incomplete. If it be incomplete, or, which 

 is the same, if the integuments scale off piece by piece, we 

 have that mode of change which is peculiar to the most 

 perfect of the Fertebrata, and to the least perfect of the 

 Annulosa. 



Complete ecdysis is the shedding of the whole external 

 envelope at once, of which we have examples among the 

 vertebrated as well as annulose animals. It is of three sorts ; 

 First, where the external envelope is shed without produ- 

 cing any essential change of form, except inasmuch as may 

 relate to the increased size. In those larvae of insects 

 which become inactive in their pupa state, such a process 

 may always be distinguished from the true metamorphosis; 

 but in Apterous Hexapods having active nympha; they are 



