THE LOWER SILURIAN ROCKS. 



I. 



Carbonate of lime 84.02 



Carbonate of magnesia 5.33 



Silica n Qo 



Alumina 2 21 



Iron sesquioxide §3 



Iron protoxide 39 



Water gi 



100.42 



561 



The following list of fossils includes all that I have observed in 

 the Trenton beds. The determinations are mostly by Mr. E. P. "Whit- 

 field: 



Name. 

 Petraia (Streptelasma) corniciilum, 



Columnaria alveolata, 



Graptolitic markings, 



Crinoidfil columns, 



Oiihis tricenaria, 



Streptorhynchus filitextus 



S. deflectus 



Stfophomena camerata, 



S. incrassata, 

 Rhynchonella, n. sp., 

 -R. n. sp., 



Tellinomya cuneata, 

 Cypricardite's ventncosus 

 Eaphistoma lenticulare 

 B. Nasoni, 



Trochonema unibilicatum 

 Murchisonia hicincta, 

 M. tricannata, 

 Pleurotomaria suhconica, 

 Helicotoma planulata, 

 Orthoceras annulum, 

 0. vertehrale, 



Gyroceras dupUcoshiturr\u. sp., 

 Oncoceras pandion, 

 Cyrtoceras, und. sp., 



Horizon at which found. 



Occurs throughout the 

 Buff but most com- 

 mon in the lower part. 



Lower part of Buff. 



Lower part of Blue. 



Upper part of Buff. 



Buff. 



Buff. 



Buff. 



Buff. 



Buff. 



Buff. 



Blue, 

 Buff. 

 Buff-. 

 Buff. 

 Buff-. 

 Buff'. 

 Buff. 

 Buff 

 Buff. 

 Buff. 

 Buff- 

 Buff. 

 Buff. 

 Buff. 

 Buff-. 



Beside these, obscure and fragmentory casts of Orthoceratites are 

 very numerous indeed in the Buif, varying greatly in size, some 

 occurring as great as 6 feet in length and 8 inches in diameter. The 

 fossils of the Buff are almost -wholly in the state of casts of the in- 

 terior, or impressions of the exterior. Of those in the list, the most 

 frequently met -with are the coral Petraia, and the gasteropods, 

 amongst which Trochonema urribilicata is the most abundant. These 

 Wis. SUR.--36 



