CARIDERPESTES. 5 



ventral plates ; (3) the appendages, appearing only on every fourtli segment, 

 are not proved to have existed on all the rest ; and seem blade-like and formed 

 for moving in water; and (4) there is considerable evidence of a peculiar 

 extremity. 



Scudder ^ certainly figures an example of Eu. armlgera^ which appears to have 

 appendages only on every alternate ventral segment, one dorsal segment covering 

 four ventral ; but he explains this by supposing the ventral segments to be really 

 only two divided plates. Moreover the genera Xylobius and Archiulus, though 

 placed in the same sub-order, do not seem to show any signs of spines. 



The signs of segmentation in the appendages are obscure, but some of those 

 organs, as figured by Scudder,^ seem so closely welded that it is quite possible that 

 in the present instance also segmentation really existed. A central longitudinal 

 line, similar to that which is strongly marked in our specimen, is described by 

 Scudder in some species of EupJioberia. 



In our fossil the lower part of a few of the segments shows marks which, 

 although very indistinct, have probably significance. Within the straight front 

 margin of the plate the surface seems raised in an indented ridge, receding again 

 backwards at the base like the mullion of a window ; and behind this are two ovoid 

 concavities, separated above by a horizontal ridge level with the angle of the 

 scallop or indentation. 



Professor Rupert Jones points out some resemblance to it in Anomalocaris 

 Canadensis, "Whiteaves,* which he thinks to be allied to Euphoheria. Whiteaves's 

 figure shows ten segments, each with two simple appendages, and a caudal extremity 

 with three pairs of irregularly placed equal spines. Our species differs from it, 

 among other points, in having the segments much narrower, and the appendages 

 very much longer. 



While, however, there is much reason for regarding this fossil as a Myriopod, 

 it bears some resemblance to the bodies of the FhyUocaridss. The latter appear, 

 as a rule, much shorter, and their segments do not generally have appendages, 

 though in Nehalia itself the two last body-somites have tufted appendages. 



Lastly, our fossil appears to be a marine organism, both because it probably 

 comes from some bed of the Lingula squamiformis series, and because the structure of 

 its appendages seems to show that they may have been natatory organs. While, 

 however, Myriopods are essentially terrestrial, Scudder shows that there is reason 

 to suppose that some at least of the Carboniferous forms were more or less aquatic. 



1 18S2, Scudder, ' Mem. Boston Soc. N. Hist.,' vol. iii, p. 160, pi. xiii, fig. 8. 



2 1868, Meek and Wortheu, ' Geol. Survey Illinois,' vol. iii, p. 556, figs, c, D. 



3 1882, Scudder, ' Mem. Boston Soc. JST. Hist.,' vol. iii, p. 143. 



* 1892, Whiteaves, ' Canad. Eecord Science,' vol. v, p. 206, woodcut. 



