EXTRACTS FOREIGN AND DOMESTIC. 165 



But his fossils, on which he rests this data, are identical with those 

 pf the Trenton limestone and the New-York slate. Some few are 

 lot identified as yet : but it is impossible to go into a new locality 

 )f an old and well explored region and not fmd some new fossils : 

 ;)ut all these others evidently belong to the same species we have 

 Ulready described as belonging to the New-York system. The 

 ^ereites of Prof. Emmons give no evidence of belonging to a 

 ower group than those of the older Silurian of England, or the 

 ^ew-York group to which they had already been referred. 



Prof. Hall then exhibited a section of the rocks from the slates 

 vest of the Hudson river, crossing the Hudson near Troy, and 

 •oine: east to the Connecticut river. He denied that these were 

 ny older than the old Silurian range of England, or than the fos- 

 illiferous rocks of the Hudson, or Paleozoic groups. He found in 

 hem trilobites and encrinal stems and univalve shells precisely 

 irailar to those of the Trenton limestone, between Troy and the 

 3wn of Adams ; and still farther east he had found that singular 

 lul characteristic fossil, the Scolithus tnhulites in the granular 

 uartz. If they were an entirely different series of rocks, as Mr. 

 Immons said they were when he called them the Taconic group, 

 e should not have found the fossils so closely allied to those of 

 le other formations. 



Pof. Rogers confirmed this view. 



Prof. Dewey still had his doubts about it. He thought they 

 ere older than the old Silurian group. 



[The views of the gentlemen who took part in this discussion 

 f the merits of the Taconic system are erroneous. They misun- 

 erstand the principles upon which the system is based. Instead 

 f being based on fossils it is really based on superposition ; the 

 )west member of the New- York system being superimposed upon 

 lose of the Taconic system unconformably. The fossils are em- 

 loyed only as collatteral evidence — and the statement made by 

 Tr. Rogers in regard to them, is far from being true — for there is 

 5t a single fossil of the taconic system which is found in the New- 

 ork system. Whoever, then, rejects the taconic system, rejects 

 le very principles which he maintains in other cases ; it would 

 ■ equally consistent to reject the evidence we have of the diver- 

 ty existing between the carboniferous and new red systems. Mr. 

 ogers says, if the so called taconic system was correct, we should 

 ive had whole mountains and plains made up entirely of this 



cup. Though we deem this remark as of little importance, 

 'W it is just what we have. The taconic range of mountains, 

 ith their valleys and plains are well known parts of the taconic 



