April, 1841.] 7 



Second Annual Report of the geology of the public lands 



belonging to Maine and Massachusetts, by Dr. Chas. T. 



Jackson. From the Author. 

 Report on the agricultural and geological survey of the 



State of Rhode Island, by Dr. Chas. T. Jackson, 1S39. 



From the Author. 

 Systema Regni Animalis, by John Christopher Exleben ; et 



Prodromus Mammalium et Avium. Purchased by order 



of the Academy. 



Written Communications. The Corresponding Sec- 

 retary read a letter from Henry Piddington, Esq., dated Cal- 

 cutta, July 26th, 1S40, in relation to the works presented by 

 him this evening : also a letter from Mr. L. W. Williams of 

 Leiperville, Delaware county, Pennsylvania, in regard to 

 the minerals presented by him this evening, and a proposed 

 exchange of specimens. 



Verbal Communications. Professor Johnson made some 

 remarks in relation to the apparent tendency of Anthracite 

 coal to assume crystalline forms ; and exhibited a specimen 

 of the rhombic form. 



Professor H. D. Rogers observed, that in his explora- 

 tions of the coal formations of Pennsylvania, he found he 

 could trace this tendency to three mechanical causes, viz : 

 1st. to planes of deposition ; 2dly. to transverse planes or 

 joints ; 3dly. to faults. 



By special permission, Prof. Johnson in the chair, 

 Dr. S. G. Morton made some observations on a mode of ascer- 

 taining the internal capacity of the human cranium, by means of 

 the tin tube and graduated rod, as described by him in Crania 

 Americana, page 283. 



The materia] hitherto used by Dr. Morton for the purpose of 

 filling the crania, was white pepper seed, which was selected on 

 account of its spherical form, and the general uniformity in the size 

 of the grains ; in these respects, however, there is sufficient diversity 

 to occasion considerable variation in the results of several succes- 

 sive measurements of the same head, especially when taken by 



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