44 



tlie town, in which a bloclv of greenstone was so imbedded as to show 

 that it fell in while the trap was in a molten state. There is a mag- 

 niticent devolopineut of porphyry at the Neck which runs submarine 

 and appears at Tinker's Island, then runs submarine and again emer- 

 ges at half-way rock. The back of the Neck is porphyry and sienite 

 with greenstone. The latter is here and there washed out so that 

 great chasms are thus produced. He accounted for the crookedness 

 of the streets of the town by stating that they followed the natural 

 valleys. Moreover, nearly all their cellars have been made by blast- 

 ing. The rock in which they are formed is very hard, so that to save 

 expense houses have been placed where the cellar could be most 

 easily obtained. Their pastures are excellent, and although used 

 through several generations grow better instead of poorer. This is 

 owing to the fact that the nourishment for the vegetation is furnished 

 largely by the disintegration of the stones abounding in them. 



Mr. C. M. Tracy of Lynn, described in a very happy style, some of 

 the plants that had been gathered. Among which were the orchis, 

 cleaver, wild bergamot, button-bush, etc. The collection of botanical 

 specimens was very large and Mr. Tracy felt compelled to give place 

 to others before a small portion only had been described. 



Mr. Alpheus Hyatt commenced a description of the large number 

 of marine specimens collected from the kelp. Remarking that it is 

 not generally known that we have native sponges, he exhibited a 

 specimen of sponge attached to the root of a kelp weed. He ex- 

 plained the structure, growth and method of development of sponges, 

 saying that they wei'e compound animals, that is, a community of ani- 

 mals, living in a common investing membrane. The utility of the 

 sponges of commerce is owing to the development of horny fibre in 

 this membrane, in the place of calcareous spiculee which form the 

 framework of our native sponges. 



Upon a muscle shell exhibited was a gelatinous spot which proved 

 under the microscope to be a community of animals belonging to the 

 class of Mollusks. and named Ascidians. They are similar in general 

 structure to the clam. A question here being asked concerning the 

 clam, Mr. Hyatt described its anatomical structure. He also passed 

 around in a bottle and described some specimens of the Bryozoa or 

 moss animals, as illustrating the composite animals call Polyzoa. 



Mr. Geoege D. Phippen of Salem, continued an account of the 

 plants. On his way to the meeting he had collected the common 

 weeds, and he proceeded to give an interesting account of their intro- 

 duction and classification. The greater part of them were introduced 

 foreigners, the gypsies of vegetation. A weed had been defined to 

 be " a plant out of place," but a true weed was more than that, being 

 troublesome and useless. 



