On the Classification of the Diplopoda. 283 



XXXV. — On the Classification of the Diplopoda. 

 By R. Innes Pocock, Assistant Naturalist Britisii Museum. 



Of the naturalists who since the time of Brandt have paid 

 attention to the Diplopoda, no two have come to the same 

 conclusions concerning the classification of the group, and 

 every one seems to have failed to appreciate fully the true 

 value of the characters which serve as signs of affinity, or the 

 converse, between its various divisions. 



In the case of the older authors this has, of course, been 

 due to ignorance of the structures which by later writers are 

 considered to be of the greatest systematic importance ; for 

 it is only comparatively of recent years that the copulatory 

 feet have been studied, and the extent of the modifications 

 presented by these organs fully realized. 



Taking into consideration existing forms there are four 

 genera of Diplopoda which may be -^selected as examples to 

 illustrate the modifications of structure presented by the 

 group. These four genera are the representatives of as many 

 divisions ; but since these divisions are by no means equal in 

 value, it is desirable to decide the • exact position that each 

 ought to occupy with regard to the others. For this purpose 

 it will be necessary shortly to treat of the structure of each of 

 these genera in turn, and briefly to state the position that has 

 been assigned to the division of which it has been taken as a 

 type by naturalists who have written most extensively on the 

 subject. 



The four genera in question are — Polyxeyiusj Glomeris^ 

 lulus ^ and Polyzonium. 



By Brandt and Newport Polyxenus was associated with the 

 Polydesmidse to form the suborder Monozonia ; by Wood it 

 was placed with the Polydesmidas, lulicl^, and Lysiopeta- 

 lidse in his suborder Strongylia ; but in 1872 M. de Saussure, 

 in his work upon the Mexican Myriopoda, suggested that 

 further observations into its structure would probably lead to 

 the abandonment of the idea that any near relationship exists 

 between Polyxenus and the other Diplopoda. Taking appa- 

 rently this suggestion into consideration, and possessing be- 

 sides greater knowledge of its anatomy. Dr. Meinert, in his 

 paper on the Chilognatha of Denmark, divided the latter 

 group into two sections — one to QonXoxxx Polyxenus^ theother the 

 Glomeridse, lulidee, and Polydesmida3. But to these sections he 

 gave no names. This deficiency was, however, in 1884, 

 supplied by Dr. Latzel, who, using the name Diplopoda as 

 synonymous with the Chilognatha of Meinert, restricted the 



