28 Annals of the Carnegie Museum. 



The writer has made a careful study of these horizons in the field, 

 and was unable to find any indication of unconformity in the section 

 in this part, and concluded, that, although Spirifer whitneyi and other 

 typical Upper Devonian forms present in 4 and 5 were not found in 

 members i and 2, as noted by Dr. Raymond, certain forms, such as 

 Rhipidomella vannxemi{l) and Productella cf. arctosiriatiis were suflfi- 

 ciently abundant in both the gray limestone, number 4, and the yellow 

 shale, number 2, which almost immediately overlies number 4 at 

 Logan, where this careful study was made, to indicate that there is no 

 sharp break in the record here. Syringothyris carteri was found in 

 the yellow shale within six feet of the top of number 4, and in the same 

 layers with R. vanuxemi{?). In the overlying yellow calcareous sand- 

 stone S. carteri is common, and is associated with Schuchertella inflata 

 and Productella cf. arctirostrata, and certain doubtfully identified 

 Spirifers. This faunule, although containing many lower IVIississip- 

 pian forms, is considered by the writer to be sufificiently different from 

 the fauna in the overlying Madison limestone, which is regarded as 

 Kinderhook, or basal Mississippian, to be considered transitional, as 

 Dr. Raymond has suggested. 



Syringothyris carteri is generally regarded as an index of Mississip- 

 pian age, but this seems to be a case where it extends down as far as 

 uppermost Devonian strata. Other species of Syringothyris have 

 been reported from Middle or Upper Devonian strata in various parts 

 of the Mississippi valley, and this genus is now regarded by Dr. 

 Schuchert^^ as having originated in the Cordilleran sea during later 

 Devonian time. 



The typical faunule of the Three Forks Formation, collected from 

 members 4 and 5, is similar in certain of its forms to that of the lower 

 Ouray limestone of Colorado and also to some of the Upper Devonian 

 forms of the eastern United States. It compares closely with certain 

 European faunules, especially those from near the Ural Mountains. 



Dr. Th. Tschernyschew^* in 1887 made the following correlation of 

 the Upper and Middle Devonian Formations of the Urals, Germany, 

 and eastern North America: 



1" Schuchert, Am. Jour. Sci., Ser. IV, Vol. XXX, 1910, p. 223. 



'8 Tschernyschew, Mem. Com. Geol., St. P., Vol. III. pp. 172-185. 1887. 



