KEMARKS ON THE NATURAL ARRANGEMENT OF THE MTRIAPODA. 243 



of Mr. Newport, with an alteration of the characters. Had that able naturalist lived to 

 make his studies of the second order as complete as those of the first, he doubtlessly 

 would so have altered his classification of the Chilognatha as to have left just as little 

 to be done in them. 



In the first part of this memoir the Iulidae were placed above the Polydesmidae. I am 

 convinced that this was an error, and that Mr. Newport is right in assigning them a 

 lower rank. On glancing over the Chilopoda it will be seen that, as we descend the 

 scale, the number of segments in the body constantly increases — or, in other words, the 

 distinctive character which separates the Myriapods from the Hexapods and Crustacea, 

 and allies them to the Annelids, — the multiplicity of segments, the absence of cephaliza- 

 tion — is exaggerated. On applying this principle, it will be at once perceived that the 

 Polydesmidae must be placed above the Iulidge, and the Glomerida?, Leach (of Newport), 

 be still higher, and thus be thrown next to the first order. 



There is one character which allies the Glomerida? to the Chilopoda, whose importance 

 has been overlooked, and which seems to me to fix their place unquestionably. It is a 

 curious circumstance that so careful a naturalist as Mr. Newport should misstate such an 

 important anatomical fact. The genitalia in the Glomerida; are placed, not as in the rest 

 of the order, in the anterior portion of the body, but in the posterior, thus agreeing witli 

 the Chilopoda. It is very interesting to see a character which, in the higher group is cha- 

 racteristic of an order, thus becoming so degraded in a lower group as to belong only to 

 suborders ; and still more so when, as in this case, the same change takes place in the 

 value of one or more other characters. On examining the mouths of the various fami- 

 lies of the Chilopoda it will be seen that they are all formed after one common type ; this 

 indeed, is so altered that there is something more or less peculiar in each ; but still there 

 is one fundamental pattern to be traced all through, from the highest to the lowest. Not 

 so in the Chilognatha ; in them there are two distinct types. The one of these, which is 

 the more aberrant from the Chilopod type, belongs to those families which are farthest 

 from that order. The two characters just spoken of do not go side by side, as it were, but 

 overlap one another ; that is, the families nearest to the Chilopoda have the genitalia in 

 the posterior portion of the body and the manducent form of mouth ; whilst those which 

 come next to these retain the latter, but have the genitalia removed forwards ; then a step 

 further and the families lose both these characters, having the sugescent mouth and the 

 anterior position of the genitalia. 



It seems to me, therefore, that we are thus brought to the three grand divisions — the 

 suborders of the Chilognatha or Diplopoda ; that these are the characters which, running 

 through the class, furnish the groundwork for its arrangement. This is confirmed by a 

 set of sub-characters, if, indeed, they ought not to be considered full characters. In these 



