P. E. Raymond — Fauna of the Chazy Limestone. 367 



ville of Kew York is the northeastern representative of " the 

 extreme top of the Stones River" group. 



In the Columbia folio referred to above, Ulrich has tabulated 

 the fossils of all the divisions of the Stones River group as 

 developed in the middle Tennessee region. In the Lebanon 

 formation, the upper member of the Stones River group which 

 is there correlated with the Chazy, there are, according to the 

 table, 37 species besides 10 undescribed Bryozoa. Of these 

 37 species, 7 are Bryozoa and 5 are not specifically identified. 

 This large number of Bryozoa — 17 species — at once suggests 

 that the formation containing them is much more closely allied 

 to the Trenton than to the Chazy. Leaving out of account 

 the Bryozoa, which in the Ordovician nearly always have a 

 very restricted vertical range, and the 5 forms not specifically 

 identified, it is found that 17 of the 25 species remaining are 

 Black River or Trenton forms. All the brachiopods, 4 of the 

 5 gastropods, and 2 of the 3 trilobites are species occurring in 

 big her formations. Even if all the described species are 

 included, 53 per cent of the species of the Lebanon formation 

 are Black River or Trenton forms. 



Below the Lebanon is the Ridley horizon, about 80 feet in 

 thickness. Of the 9 species listed from this formation, 6 are 

 found in the Black River. 



Below the Ridley is the Pierce limestone with 12 species 

 listed and 20 undescribed bryozoans. Only 11 forms are 

 specifically identified and of these 30 per cent are Black River 

 or Trenton forms. 



The lowest member of the Stones River group is the Mur- 

 freesboro, which is about 60 feet in thickness and contains 21 

 species, 21 of which are identified. The fauna is composed 

 principally of Mollusca, of which gastropods of the genera 

 LojyJiospira and Liosjpira are particularly numerous. Of the 

 21 species, 11 are Black River or Trenton forms, so that 52 

 per cent of the species in this oldest member of the Stones 

 River group belong to the Black River or Trenton. 



This analysis may be tabulated thus : — 



Lebanon 



Ridley 



Lebanon. 

 .... 25 

 1 



Rid- 

 ley. 



3 

 2 

 4 



Pierce, 

 1 



9 

 1 



Murfrees- 

 boro. 



1 

 21 



Black 

 Eiver. 



4 

 1 

 1 

 4 



Tren- 

 ton. 



7 

 1 



Pierce 



4 



2 



]Murfreesboro__ . 



3 



7 



Of the 58 described species occurring in these 4 subdivisions 

 of the Stones River, the above table shows that 27, that is, 46 

 per cent, occur in the Black River and Trenton formations. 



