490 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



as that of the Madison limestone, and had the material been worked by the 

 same hand the specific determinations would doubtless have been more 

 uniform. The two areas are geographically closely related. 



Considering the fauna of the Madison limestone as a whole, it can be 

 pointed out that, of the 79 species known from this formation, 29 were 

 described from or have been identified in Kinderhook beds of Ohio, Michi- 

 gan, and the Mississippi Valley — that is, about 37 per cent of the Madison 

 limestone fauna consists of Kinderhook species These are: Michelinia 

 placenta, Platycrinus symmetricus, Crania Icevis, MMpidomeUa michelini, Ortho- 

 thetes ineequalis, Derby a JceoJcuk (7), Leptcena rhomboidalis, Chonetes loganensis, 1 

 Chonetes ornatus, Productella cooperensis, Productus l&vicosta, P. semireticii- 

 latus, Camarophoria ringens, Camarotoschia herrickaua n. sp., C. metallica, 

 C. camarifera (?), C. sapplio (?), Dielasma utah, 2 Spiriferina solidirostris, 

 Spirifer centronatus, S. subattenuatus, S. marionensis (?), Beticularia cooper- 

 ensis, B. (7) peculiaris, R. (?) subrotundata, Syringothyris carteri, Athyris 

 lamellosa, Cliothyris crassicardinalis, and Conocardium pidclielhim (?). 



After making the necessary deductions from this list, some of whose 

 identifications are rather in the nature of approximations, it still must be 

 apparent that the fauna of the Madison limestone has many peculiarities of 

 the earlier Mississippian, and in particular shows a marked affinity through- 

 out with the Kinderhook fauna. 



Taking a more general view of the fauna, the presence of Syringothyris 

 speaks for lower Mississippian, since it is not known there above the Keokuk, 

 and the same is true of Leptcena rhomboidalis, since it does not occur above 

 the lower Burlington. It must be noted, however, that these forms 

 appear to be restricted to the lower portion of the Madison also. The 

 absence of Productus punctatus from this formation is evidence in the same 

 direction, as it is introduced in America in the Keokuk, and in general 

 there is to be noticed in the Madison limestone fauna an absence of those 

 highly differentiated and often peculiar species which characterize the 

 beds of the middle and upper Mississippian. This is perhaps most noticeable 

 in the Spiriferoids and Productoids, for they are the commonest forms. In 

 the Madison these comprise a few comparatively simple, stable, and persistent 



■A form, probably the same, is common in the Cuyahoga shale of northern Ohio, passing usually 

 as C. illinoisensis. 



-Probably a synonym for 1). httrlinijtonense. 



