JEFFERSON COUNTY. 

 111. 



105 



1. CjTJricardites angustifrons. 



2. Cypricardites ovata. 



The preceding figures are offered as an illustration of the palceontology of the Champlain 

 group. I have been able to furnish the most important of all the sedimentary rocks of the 

 Second district, the principal motive having been to give accurate drawings, by means of 

 which comparisons could be made with the fossils of other rocks in other portions of the State 

 and country. I have not deemed it so necessary, in this place, to settle and clear up all doubts 

 as it regarded identity of species, as to obtain good figures for comparison. I have therefore 

 omitted the specific names in several instances, considering these as of little consequence in 

 comparison with the determination of the position and range of the fossils themselves. 



In this connection, I may remark farther, that it will be seen from the preceding figures, 

 that all the sedimentary rocks of the Second district are fossiliferous, and that the lines of de- 

 markation between the rocks are very strongly defined by the fossils alone. To the practised 

 eye, very little difficulty is experienced in distinguishing the rocks by means of their litho- 

 logical characters ; but it is only by means of the fossils, represented truly in drawings, that 

 correct comparisons can be made abroad. These enable the geologist to institute at once 

 those comparisons which are necessary to establish identities or .differences between rocks at 

 a distance. Though a minute detail be given of the lithological characters of a group, still 

 it is impossible to present it as it is ; but when an accurate figure is given of an imbedded 

 organic body, there is furnished at once as it were a living character, one that is far more 

 constant than even the mineral character of the group or rock itself. 



