FOSSILS OF TIIK COAL MKASUJKS. <;i) 



which are sharp. On its upper side there is a well defiued 

 mesial earina. with a slightly concave slope on each side to 

 the lateral edges; thus presenting much the appearance of 

 a broad, miniature bayonet. The stylets have each on the 

 flattened under side about six or seven small, longitudinal 

 ridges, and on the upper side a distinct longitudinal mesial 

 earina, between which and the lateral margins there is on 

 each side a smooth, rounded concavity, or broad furrow; 

 along each lateral margin there are two closely approxi- 

 mated carime, one above and one below, with a narrow 

 sulcus between. 



Length of telson, about 0.75 inch; breadth of do., 0.12 

 inch: length of stylets, about 0.80 inch; breadth of do. near 

 the articulating end. 0.12 inch. 



This species will I.K? readily distinguished from I). Neoi/fr/v, of McCoy, 

 by its proportionally broader, and more lanceolate stylets ami telson, 

 the latter of which also differs in being smooth above, instead of marked 

 with divaricating stria-, as in the Scouleri. Its stylets are also flatter, 

 and carinated instead of being rounded. From Portlocfs C. Colei, it 

 will be distinguished by having the cariuae of its stylets and telson 

 smooth, instead of crenate. 



So far as we are informed, this is the n'rst species of this genus found 

 in America. It is another example of a very decided Carboniferous genus 

 added to the many others now known to be associated in the Coal 

 Measures of Illinois, with numerous fossils that occur in Coal Measure 

 rocks on the Missouri, in Nebraska, that have been by some geologists 

 wrongly referred to the Permian (=Dyas). 



:Iity and position Xear the middle of the Coal Measures, at Dan- 

 ville, Illinois ; associated with numerous upper Coal Measure fossils. 



