27 



had been making a special study of these peculiai' and little 

 known growths the past year. 



Mr. Bouve made a few remarks upon the origin of Tgneous 

 Rods, comparing specimens of the igneous rocks of New Hamp- 

 shire and lava from Vesuvius, to illustrate the resemblances and 

 differences between quick and slow crystallization. 



After these interesting and instructive observations, followed 

 by the interchange of much general information in a more private 

 manner, and after passing votes of thanks to Mr. Bouve for his 

 untiring exertions throughout the day, and to Col. Boyd for his 

 most welcome hospitality, the Society took the cars for Boston, 

 and returned Avell satisfied that a day could not have been more 

 agreeably and more instructively passed ; and the hope was uni- 

 versally expressed that this excursion might be the first of a 

 series, which would inevitably tend to augment the usefulness and 

 prosperity of the Society. 



Avgust 6, 1856. 



The President in the Chair. 



Prof, William B. Rogers exhibited to the Society 

 several specimens of rock, containing casts of portions 

 of a large Trilobite lately obtained by him from a 

 locality on the north edge of Braintree, about ten miles 

 south of Boston. 



Prof. Rogers adverted to the great interest of this discovery as 

 furnishing the first clear evidence yet obtained as to the geologi- 

 cal age of any of the extensive series of altered rocks which 

 occupy a large part of eastern Massachusetts and the neigliboring 

 States. 



Hitherto, geologists have not been aware of the existence of 

 any fossil forms in these strata, as none are referred to in the 

 Geological Report of Prof. Hitchcock, or in any of the subse- 



