Beedk.] Carboniferous Invertebrate*. 11 



the larger ones possessing the larger and more numerous spines, 

 while those with fine costse seem to be nearly destitute of spines. 

 The forms of this species with the front margin emarginate 

 are restricted, or at least seem to be, to the base of the Upper 

 Coal Measures, and are for this reason worthy of varietal dis- 

 tinction. There is also a very wide form that is very much less 

 gibbous than the ordinary form, which is likewise restricted to 

 the same rocks as the preceding, and will probably prove varie- 

 tally distinct from the species. Waagen B suggests that Pro- 

 ductus eorei should be divided into two series of forms, one with, 

 and the other without a mesial sinus in the visceral area. This 

 will hardly hold for our western forms, for those of the form 

 described by Swallow as P. eimericanus and those without the 

 fold characteristic of that form both possess the sinus. The 

 form that is the most common in the Kansas Coal Measures is 

 that described by Norwood as P. prattenianus, found abundantly 

 at the Nebraska City, Neb., locality of Meek, and throughout 

 the Kansas Coal Measures. 



Productus cora americanus. Plate XI, fig. 2. 



Product us a an ricanus Swallow, Trans. St. L. Acad. Sci., n, p. 91, (1863). 



xvii-a, If. 22, 23, (1893). 

 Productus (equicostatus Hall (non Shumard), Pal. N. V., vni, pt. i, pi. 



This shell differs from the preceding species in possessing a 

 fold in the anterior portion of the shell, which is less developed 

 anteriorly than the sides, forming a deep sinus in the anterior 

 margin. In the most distinct forms of the variety the shell 

 is sometimes less gibbous and more alate than is true of the 

 species. 



Range and distribution: Upper and Lower Coal Measures ; 

 Kansas City, Eudora, Anderson county. Seems to be confined 

 to the base of the Upper Coal Measures and to the Lower Coal 

 Measures. 



5. Pal. Indica. Salt Ranpe Foss., 676. 



