240 



REMARKS ON THE NATURAL ARRANGEMENT OF THE MYRIAPODA. 



into two separate segments, the posterior of which gives origin to the immense foot-jaws, 

 whilst in the Chilognatha the head is composed of but a single segment. An apparent 

 contradiction of this exists, however, in the Cermatiidae. When viewed from above, the 

 head of one of this family appears to consist of but a single segment ; but this is 

 merely because the two cephalic scuta are fused together and consolidated into one, just 

 as two body scuta are. The sternum of the posterior segment is entirely separate, and 

 bears the foot-jaws as in the other families. In like manner, in the Lithobiidae, the 

 second cephalic scutum is very small, agreeing with the smaller scuta of the body. 



The arrangement of the Chilopoda adopted in this memoir is very nearly that of 

 Mr. Newport, which appears to be the true exposition of the plan of their creation. His 

 families are natural, and are grouped according to their affinities. The Cermatiidse de- 

 servedly stand at the top, on account of their more perfect organization and approach in 

 some characters towards the Hexapoda. They have, as has been just stated, but a single 

 scutum to two segments. In the Lithobiidae the posterior scuta of each pair is atrophied, 

 evincing a tendency to disappear, and, at the same time, the antennae are almost multiarti- 

 culatc. It is evident how these two facts ally them to the Cermatiidce, and indicate a posi- 

 tion at the top of the Holotarsia, which is confirmed by the fewness of the segments of the 

 body and their active habits. On the other hand, the tendency of the first subsegments 

 to become enlarged and approach the Diplopod type in the Geophilida), indicate their 

 position as low in the scale, which is also confirmed by the great number of the segments 

 of the body and the poorly developed nervous system. 



Dr. Leach (Linn. Trans., xi), M. Gervais (Apteres, vol. iv), and Mr. J. E. Gray (Enycl. 

 Anat. Phys., art. Myriap.), have placed the Chilopoda below the Chilognatha, a position 

 which is totally repudiated by their more highly developed nervous and vascular systems, 

 as well as by their habits and external" form. They are the carnivora of the Myria- 

 poda, and undoubtedly are superior to the vegetable feeders. 



There have been offered, within a few years, three different classifications of the Chilog- 

 natha, by Messrs. Newport, J. E. Gray, and J. E. Brandt. Mr. Lucas has also published 

 a synopsis (Hist. Nat. des Crustac. des Arachn. et des Myriap., tome iv, 1840), to which 

 I have not had access, but, according to Mr. Newport, it differs from that of M. Gervais 

 only in the names of the families. 



J. E. Gray {he. cit.) proposes to divide the Chilognatha into six families, the Iulidje, 



CrASPEDESOMID/E, POLYDESMIHiE, GLOMERIDyE, ZepHRONIDvW, and POLYXENIDyE. He does not 



attempt to arrange these into higher groups, and totally ignores the existence of the 

 Sugentia ! His Craspedesomidce is probably the same family as that known in this paper 

 as the Lysiopetalidce,, and the others appear to correspond with those of the same names, 

 although his characters are very different. 



