V. Archtpolypoda, a Subordinal Type of Spined Myriapods from the Carbon- 

 iferous Formation. By Samuel H. Scudder. 



Read January 5, 1881. 



.ALL the paleozoic myriapods which have been published, only fifteen nominal species 

 in all, have been referred to the Diplopoda or Chilognatha as they are variously termed. 

 Among them are species which seem to bear a very close general resemblance to modern 

 Iulidae, and some of them have even been described under the generic name lulus. 

 Others, however, first made known as myriapods by Messrs. Meek and Worthen 

 in 1868, in the Proceedings of the Philadelphia Academy of Natural Sciences, and in the same 

 year figured in the third volume of the reports of the Illinois Geological Survey, differ strik- 

 ingly from modern types in the presence of rows of very large forked and branching spines 

 upon the surface of the body. These naturalists were able also to show the probability tbat a 

 fossil from the coal measures of England which Mr. Salter had referred to the crustacean 

 genus Eurypterus belonged in the same group, and more recently Mr. Henry Woodward 

 has pointed out that not only this form, but another, known since the publication of Bro- 

 die's work on the English Fossil Insects in 1845, and which was supposed by Westwood to 

 be the larva of Saturnia, a genus of Lepidoptera, should certainly be referred to this group 

 of spiny myriapods ; and to the list Woodward has also added another species. 



Having enjoyed the opportunity, through the kindness of Messrs Carr, Worthen and 

 Pike, 1 of examining a considerable number of specimens of these curious fossils — all from 

 the ironstone nodules of Mazon Creek, Illinois — I bring here the results of my study, 

 which show that these spined myriapods, while allied to the Diplopoda rather than to the 

 Chilopoda, certainly form a very distinct type, which was no doubt the precursor of the 

 Diplopoda ; and it appears very probable that even those paleozoic species which have 

 been supposed to resemble closely the modern Iulidae were also spined, and may therefore 

 be presumed to have resembled their evidently spined relations in other points of structure 

 in which the latter are distinguished from modern forms. The reasons for this belief will 

 be given further on. 



One main distinction between the two groups, Diplopoda and Chilopoda, into which mod- 

 ern Myriapoda have been divided, consists in the relation of the ventral to the dorsal 

 plates of the body segments. In the Chilopoda there is a single ventral plate, bear- 

 ing one pair of legs, to every dorsal plate. In the Diplopoda, on the contrary, there are 



1 A considerable number of specimens, including some new Carr, Pike, Armstrong and Bliss, advantage has been taken 

 species, having been sent me after the first presentation of of the delay in its publication to introduce into the text 

 this paper to the Society, through the kindness of Messrs. descriptions of all such additions. (Jan. 31, 1882). 



