140 



Mr. Levi/ on a neio MUieral. 



[Feb. 



Siphonaria angulata. Testa convexo conica, angulata radiato- 

 costata; intus fusca. long. 15-10 unc. 



Parmophorus elegans. Emarginula breviusculas, Sow. 

 Gen. f. 2, certainly not Parmophorus breviusculus of Blainville, 

 as that shell is in the Museum, and is only slightly antiquated. 

 Inter Parmophoros et Emanginulas. 



Emarginula cristata. Testa convexo-conica, antice costa 

 media cristata ornata. 



{To be continued.) 



Article X. 



An Account of a new Mineral. By M. Levy, MA. in the 



University of Paris. 



(To Mr. Children.) 



DEAR SIR, 

 Through your kindness and that of INIr. .Tames Sowerby, I 

 have been enabled to examine some well-defined single crystals 

 of a substance found at Snowdon, which had been classed by 

 some with rutile, by others with sphene, but which certainly 

 differs from both, its forms being derivable from a right rhombic 

 prism, whilst the primitive form of rutile is a square prism, and 

 that of sphene an oblique rhombic prism. The forms of this 

 substance I have observed are represented by figs. 2, 3, and 4, 

 and although I have not drawn the inferior summit, some of the 

 planes which belong to it occur in some of the crystals. They 

 are flattened parallel to the planes A', and some are more than 

 half an inch in breadth and length. They cleave easily in a 

 direction parallel to the plane g', but the face of cleavage is 

 rather dull. All the natural planes are sufliciently brilliant to be 



Fig.: 



s/. 



m 



