Allen.] 178 [December 15, 



on Metaraorphism.) He would ask Mr. Shaler what his syenite was 

 made of? What sediments were thus so strangely metamorphosed 

 into a crystalline salt, like feldspar, the chief ingredient of syenite 

 rocks? Was it an ordinary sandy sediment? If so, whence did it 

 derive its potash and soda, twenty five pounds of which enter into 

 the composition of every cubic foot of syenite. And again, why do 

 we not see some unaltered grains, some coarse, unchanged gravel in 

 syenites? Nothing of the sort is ever seen, but, on the contrary, 

 clearly defined crystallized feldspar, mixed with distinct crystals of 

 hornblende and a little quartz; all of which seem to have crystallized 

 at a single jet from a stiff pasty mass which showed no subsidence of 

 separate crystals or of intermixed gravel. Dr. Jackson also said 

 that when it is alleged that crystallized rocks, like syenite or granite, 

 are altered sedimentary rocks of aqueous origin, we require that the 

 passage state should be demonstrated, and this has never been done 

 by any one who has advocated such a metamorphosis. 



From Nova Scotia to Georgia, and from the Atlantic to the Pacific 

 coasts, all granites and syenites bear unequivocal evidence of their 

 igneous origin and elevation through the superincumbent strata. It 

 is too late to revive the old doctrines of Werner, for the same evi- 

 dence with which Hutton overthrew that theory, still exists in the 

 localities pointed out by the eminent Scotch geologist, 1 and similar 

 evidence may be seen in almost any part of New England. 



December 15, 1869. 



The President in the chair. Thirty persons present. 

 The following paper was presented : — 



Notes on the Mammals of Iowa. By J. A. Allen. 



The present list of the mammals of Iowa is based mainly upon 

 notes gathered during three months spent in that State in the summer 

 of 1867, for the purpose of collecting and studying its animals and 

 plants. It seeming desirable to make the list a complete one, a few 



1 See Playfair's illustrations of the Huttonian theory for descriptions of Euro- 

 pean localities. 



