284 Mr. E. I. Pocock on the 



latter group to the families Glomericlae, lulidte, Polydesmideej 

 &c., gave to Polyxenus (Meinert^s other section) the name 

 Pselaphognatha, and made them both suborders of his order 

 Diplopoda. This arrangement was adopted by Dr. Haase 

 (' Schlesiens Diplopoden ') in 1886, and in this position 

 Polyxenus will probably remain. 



The characters by which it may be separated from all the 

 other Diplopoda are as follows : — The body is soft and clothed 

 with tufts of scale-like hairs; there is a distinct labium ; the 

 second pair of jaws do not form a plate resembling the 

 gnathochilarium ; there are no foramina repugnatoria ; the 

 anus is in the last segment but one. 



Against the third and fourth of these distinctions it may 

 be urged that no true gnathochilarium is present in Siphono- 

 phora, and that there are no foramina repugnatoria in the 

 Chordeumidas. To the former objection reference will be 

 made later on ; with regard to the latter it may be said that 

 the whole organization of the Chordeumidge points to close 

 relationship with the lulidgej and that therefore it is fair to 

 assume that tlie absence of foramina repugnatoria in the 

 former family is due to atrophy. This of course may be, 

 and very possibly is, the* case with Polyxenus ; but until 

 allied forms possessing them be known, the assumption that 

 these glands have never existed, as such, can certainly be 

 defended. 



As opposed to the above characters of Polyxenus, for which 

 as a group-name the term Pselaphognatha (Latzel) may be 

 retained, the characters of the rest of tlie Diplopoda, or, as 

 Dr. Latzel has called them, the Ohilognatha, may be briefly 

 summarized as follows : — Body hard and chitinous, destitute 

 of tufts of scale-like hairs ; there is no distinct labrum ; the 

 second pair of jaws form a plate (the gnathochilarium) ; 

 foramina repugnatcn'ia are present j the anus is in the last 

 segment. 



Within the limits of the group Ohilognatha thus defined 

 fall the three remaining genera Glomeris, lulus, and Polyzo- 

 nium. 



In 1865 Wood recognized that the peculiarities of the 

 genus Qlomeris are sufhcient to warrant the formation for its 

 reception of a group equivalent to the Monozonia and Trizonia 

 of Brandt taken together. For this group he retained the 

 old name Pentazonia, and, abolishing the Monozonia and 

 Trizonia, gave to the lulida3, Polydesmidse, and Lysiopeta- 

 lidaa the name Strongylia. But although with the views of 

 Wood concerning the affinities of Glonieris, those of M. de 

 Saussure and of Mr. G. C. Bourne (Journ. Linn. Soc. xix. 



