151 



of magnesia and iron replace in part the alumina and water. 

 [These results Mr. Hunt reduces into one of the typical forms 

 which Mr. Laurent has deduced from his researches on the na- 

 tural silicates. This requires a ratio between the oxygen of the 

 silica and that of the other oxyds of 5 : 4, and that of the silica 

 being 26.60, theory demands for the bases 21.28, while ex- 

 perience gives 21.11.] Deducting the carbonate of lime, the 

 composition for 100 parts is given below, the first column of figures 

 representing the proportions actually obtained, and the other 

 those required by theory based on the formula. 



10.78 



100.10 99.85 



As the entire paper will appear in the Journal of the Society, 

 it is not necessary to give here the details of the analysis and the 

 formula deduced, which it is difficult to print. From its hardness 

 and specific gravity, the mineral is evidently to be referred to the 

 order Zeolite; from its density it is comparable with Datholite, 

 Prehnite, and Lazulite, to which it is much inferior in hardness; 

 while from the rare species, Edingtonite, to which in hardness 

 and density it is closely allied, it is distinguished by its crystalliza- 

 tion. Mr. Hunt ofiers it as a new mineral species, which will 

 take a place by the side of Edingtonite ; and to connect the name 

 of one who has been one of the most successful cultivators of 

 mineralogy with his favorite science, proposes for it the designa- 

 tion of Algerite. 



Two specimens of this mineral were presented by Mr. 

 Alger. 



Dr. Gould continued his descriptions of the Shells brought 

 home by the U. S. Exploring Expedition. 



BucciNUM (Bullia.?) velatum. Testa solida, ovato-lanceo- 

 lata, levis, polita, livido-violacea, albido-reticulata, versus labrum 

 pallescens, et lineolis rubiginosis cincta : spira acuto-conica, anfr. 



