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study of Natural History in country places is attended, and made 

 some suggestions by wliich he thought they might be obviated. 

 In conclusion, he set forth the attractiveness of the study, strongly 

 advocating it as a means of refining and improving man's moral 

 sensibilities, and sharpening and invigorating his intellectual 

 povi^ers. 



At the close of the Address, on motion of Dr. Storer, it 

 was unanimously voted, that the thanks of the Society be 

 presented to Rev. Zadock Thompson for his interesting and 

 instructive Address. 



Prof. Agassiz next addressed the Society on the subject of the 

 classification of some of the Mollusca, particularly those of the 

 order Acephala. He showed that the genera Cyclas, Unio, and 

 Anodon agree in the arrangement of the tentacles above and 

 below the mouth, in the form of the foot, and the nature of the 

 epidermis ; whereas other characters, which had been regarded 

 as distinctive, such as the length of the syphon tubes, are falla- 

 cious. In the Unio a syphon tube exists, bringing it in close 

 alliance with Cyclas, although it is so short as not to protrude 

 beyond the shell. In Cyclas the young are developed one at a 

 time, between the gills, and at the time of birth are one half the 

 length of the parent. The first young are produced at the third 

 year of the parent. The place in which the young are developed 

 affords another point of analogy between Cyclas and Unio. 

 Prof Agassiz stated that he had found that the foot in Cyclas is 

 extended by the introduction of a quantity of water into its 

 interior. 



Three living specimens of Menohranchus maculatiis, 

 brought from Lake Champlain by Rev. Zadock Thompson, 

 were placed upon the table for the examination of the 

 Society. 



