301 



April 15, J 862. 

 The Institute met: Present Messrs. Munsell, Pease, Pa- 

 terson, Brown, Hongh and Murray, who not constituting a 

 quorum, adjourned. 



April 29, 1862. 



On motion, Hon. John Taylor presided. 



Thomas Symonds, nominated at the last meeting, was 

 unanimously elected a resident member. 



Dr. Willard presented three Danish books to the Library 

 of the Institute. 



Prof. Hall then proceeded to present his communication 

 in relation to the Niagara Group of Rocks. He pointed 

 out how rocks of the same age are determined, viz.: by the 

 fossils found in them, and then traced out the limits and 

 extent of this group in the United States and Canada. He 

 explained that it was often difficult to determine cotempo- 

 rary fossils when the districts were far removed from each 

 other, because in former geological periods, as well as at 

 present, the fauna of different regions varied very widely. 

 He showed by a comparison of the fossils of New York 

 and Indiana of the same age, how much these varied. 

 Another source of difficulty lay in the great difference in 

 appearance of the same fossil, owing to the difference of 

 the material in which it had been embedded. 



Prof. Hall illustrated these principles in Palaeontology by 

 the exhibition of numerous specimens of fossils from his 

 own cabinet, especially of crinoids, corals, &c. 



Prof. Hall also described a new crustacean, a new genus, 

 from the Potsdam sandstone, not yet described. 



Dr. Willard read a paper upon Army Surgery, with spe- 

 cial reference to the condition of our present army. He 

 pointed out the true sphere of the army surgeon, not so 

 much a practitioner to give medicine in sickness, as to at- 

 tend to the sanitary regulations of the army and prevent, 

 by the use of proper means, the numerous diseases to which 

 camps are liable. Dr. Willard stated that he had prepared 



[Trans, iv.] 40 



