150 



CHAPTER IV. 



Class III. AMETABOLA. 



THE third class, AMETABOLA, as extended by MacLeay, com- 

 prises such of the apterous insects of Linnaeus as breathe by 

 tracheae, have the head distinct, are not subject to metamor- 

 phoses (being only liable to a series of moultings, during 

 which an increased number of segments and of legs is ob- 

 tained), and have a greater or less number of legs than cij^lit : 

 the eyes generally consist of small simple granular lenses 

 like ocelli. 



These insects were arranged by Lamarck as a distinct sec- 

 tion of the Arachnida, under the name of Arachnides anten- 

 nistes, and comprise the Linnaean genera Scolopendra, lulus, 

 Lepisma, Podura, and Pediculus. The first two of these ge- 

 nera were constituted into a distinct order by Latreille, under 

 the name of Myriapoda, whilst Dr. Leach raised the three 

 others to a class under the name of Ametabola, divided into 

 two orders. 



Mr. MacLeay adopted the views of Lamarck, in regarding 

 all these insects as belonging to the same class (but added 

 thereto certain Vermes), and proposing for the class the 

 name given by Leach to a portion of it, as above mentioned. 



Rejecting the introduction of the Vermes into the class, it 

 is divisible into the four following Orders : 



