1 84 



ANNULOSA. 



gamated that the legs appear to be arranged in double pairs, 

 and by having antennas of six or seven joints. In the Pauro- 

 poda is the single genus Pauropus, characterised by having 

 only nine pairs of legs, and the antennae bifid, with three 

 long multi-articulate appendages. 



Fig. 126. Millipede (lulus). 



The oldest-known Myriapods occur in the Coal-measures, 

 the two best-known] genera being Xylobius and Archiulns. 

 These genera belong to the order Chilognatha, and comprise, 

 therefore, vegetable-feeders. In Xylobius (fig. 127) the seg- 



Fig. 127. Xylobius Sigillarice, a Carboniferous Myriapod. (After Dawson.) 

 a, Natural size ; b, Anterior portion, enlarged ; c, Posterior portion, enlarged. 



ments are divided by cross sutures into numerous fragments, in 

 a manner wholly unknown amongst recent forms. Several 

 species of this genus are known, of which the one figured 

 above derives its specific name from the fact that it is found 

 in the hollow trunks of Sigillaria. It must have possessed, 

 like the living Gallyworms, the power of rolling itself up into 

 a ball (Dawson). In the allied genus Archiulus, the segments 

 are not broken up into fragments, as they are in Xylobius. 

 The characters of both these genera are so peculiar that they 

 have been placed in a separate family under the name of 

 :Archiulidcz.\ Other Myriapods have been discovered in the 

 Carboniferous Rocks of North America and Britain, and have 

 been referred to the genus EupJwberia. The true place of 



