404 ARACHNID A, MYRIAPODA, AND INSECTA. 



power of rolling itself up into a ball (Dawson). In the 

 allied genus Archiulus, the segments are not broken up into 

 sections, 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 Archiulidce. Other Myria- 

 pods have been discovered in the Carboniferous rocks of North 

 America and Britain, and have been referred to the genus 

 Euphoberia (fig. 255). The true place of this genus is some- 

 what uncertain, owing to its possession of several abnormal 

 features, though there can be little hesitation in referring it 

 to the Chilognatha. Thus the dorsal surface shows a series 



Fig. 255. Portion of the body of EupJioberia armigera, from the Coal-measures of Illinois, 

 of the natural size (after Meek and Worthen). The dark spots on the dorsal shields are pits 

 left by the breaking off of the dorsal spines. 



of large shields, which are armed with projecting spines, 

 each of these shields corresponding with two ventral seg- 

 ments. Each of the latter bears a pair of slender, appa- 

 rently five-jointed legs. 



In the succeeding period of the Permian, Professor Geinitz 

 lias described a Myriapod from the base of this formation 

 (Hothliegende), under the name of Palceojulus Dy adieus. Like 

 its Carboniferous predecessors, it occurs in association with 

 the remains of plants (Araucarites). 



In the Secondary rocks, the Lithographic Slates of Solen- 

 hofen (Upper Jurassic) have yielded the remains of an 

 animal which is referred by Count Mlinster to the Myria- 

 poda, under the name of Geophilus proavus. Other Myria- 

 pods, lastly, have been described from Tertiary strata and 

 from amber. 



CLASS INSECTA. 



The Insects are Articulate Animals, in which the head, 

 thorax, and abdomen are distinct from one another. The 



