MISSISSIPPIAN OF PHELPS COUNTY, MISSOURI 573 



Arthropoda 



*Phillipsia tuber culata M. & W. 

 Griffithides sedaliensis Vogdes 



A careful comparison of this fauna with the extensive collection 

 in the Walker Museum, from the Keokuk and Warsaw formations 

 from a number of localities in the Mississippi Valley, has indicated 

 the approximate age of the fauna, but does not allow it to be 

 placed exactly. Its affinities are with the Upper Keokuk and 

 Lower Warsaw. What little evidence there is seems to favor the 

 placing of this bowlder in the Lower Warsaw. 



Spiriferina norwoodana, Pustula biseriatus, Delthyris similis, 

 Fenestella exigua, F. funicula, F. compressa var. nododorsalis, Poly- 

 pora gracilis, and Pinnatopora conferta occur in the Lower Warsaw 

 at a number of localities. Eumetria verneuiliana, Pseudosyrinx 

 keokuk, and Monolipora beecheri, while found in both formations, 

 appear to be more abundant in the Lower Warsaw. On the other 

 hand, Fenestella rudis, F. regalis, Polypora hallana, and P. maccoyana 

 have heretofore been identified from the Keokuk only. Spirifer 

 rostellatus is well known in the Keokuk, but its presence in the War- 

 saw has been regarded as doubtful. 



An interesting recurrent Burlington association appears in this 

 bowlder, the species of which are indicated in the faunal list by an 

 asterisk. A few other species which are common to many Mis- 

 sissippian formations are indicated by the dagger. This recurrent 

 element corresponds almost exactly to the faunas assigned to the 

 Burlington white chert. It is known at the present time that such 

 a recurrent group of species does occur either in the top of the 

 Keokuk formation or in the base of the Warsaw, in southeastern 

 Missouri, and this bowlder was undoubtedly from this horizon 

 originally. 



Closely related to the fauna just described are the three faunas 



listed below: 



Bowlder 13 — Locality 10 



Archimedes owenanus Hall 



Missouri Bureau oe Geology and Mines, Collection No. 4, Locality 12 



Archimedes grandis Ulrich 

 Orthotetes keokuk (Hall) 

 Productus ovatus Hall 



