Page:Wood 1865 - The Myriapoda of North America.djvu/108

Rh 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 lulidæ were placed above the Polydesmidæ. 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 cephalization—is exaggerated. On applying this principle, it will be at once perceived that the Polydesmidæ must be placed above the Iulidæ, and the Glomeridæ, Leach (of Newport), be still higher, and thus be thrown next to the first order.

There is one character which allies the Glomeridæ 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 Glomeridæ are placed, not as in the rest of the order, in the anterior portion of the body, but in the posterior, thus agreeing with the Chilopoda. It is very interesting to see a character which, in the higher group is characteristic 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 families 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