CHARACTERISTICS OF INSECTS AND THEIR RELATIVES 



25 



absent. The oral appratus is suctoral, and consists of three pairs of 

 gnathites. There are three pairs of thoracic legs, and three pairs of 

 vestigial abdominal legs. The abdomen is composed of eleven segments 

 and a telson. The opening of the reproductive organs is unpaired, and 

 near the hind end of the body. The head bears a pair of organs, termed 

 pseudoculi, the nature of which has not been definitely determined. 



The known members of this 

 class are very small arthropods, 

 the body measuring from one- 

 fiftieth to three-fiftieths of an 

 inch in length. The form of the 

 body is shown by Figure 36. 



These exceedingly interesting 

 creatures are found in damp 

 situations, as in the humus of 

 gardens; as yet very little is 

 known of their geographical dis- 

 tribution, as almost all of the 

 studies of them have been made 

 by two Italian naturalists. 



The first discovered species 

 was described in 1907 by Pro- 

 fessor F. Silvestri of Portici, who 

 regarded it as the type of a 

 distinct order of insects, for which 

 he proposed the name Protura. 

 Later Professor Antonio Berlese 

 of Florence described several 

 additional species, and published 

 an extended monograph of the 

 order (Berlese '09 b}. 



Professor Berlese concluded 

 that these arthropods are more 

 closely allied to the "Myriapoda" 

 and especially to the Pauropoda 

 than they are to the insects, and changed the name of the order, in 

 an arbitrary manner, to Myrientomata. 



It seems clear to me that in either case whether the order is 

 classed among the insects or assigned to some other position it should 

 be known by the name first given to it, that is, the Protura 



Fig. 36. Acerentomon doderoi: A, dor- 

 sai aspect; B, ventral aspect; 1,1,1, 

 vestigial abdominal legs (After 

 Berlese). 



