NATURAL SCIENCES OF PHILADELPHIA. 24T 



nated, with one extremity flat, and the other three-sided, with the 

 angles or borders truncated. 



Sometimes the cr3'stals occur opaque, dark green at one end, 

 becoming bright grass-green and transparent at the middle, and 

 passing into cherrj^ or rose-red and transparent at the other end. 

 Occasionall}' the green color is nearlj- absent, and we have an 

 achroite with a greenish hue, passing successively into a deeper 

 shade of green and dark green, or into pink and deep cherr^'-red, 

 usuallj^ sheathed with a thin laj-er of greenish hue at the oppo- 

 site end. 



In a cr3'stal exhibited, measuring four inches in length by three- 

 fourths of an inch in diameter, flat at one end, and three-sided at 

 the opposite end, the first inch is dark opaque green, the second 

 inch is bright grass-green and transparent, the third inch is pale 

 pink within and pale green without, and the fourth inch is cherry- 

 red within and pale green without. 



A segment exhibited of a transparent prism of achroite, an inch 

 long and an inch and a half in diameter, has upon one end a patch 

 of cookeite. This mineral often occurs investing the ends, frac- 

 tured surfaces, and sides of the tourmalines. 



Another specimen exhibited consists of a crystal an inch and a 

 half long and ten lines thick, with a three-sided termination, 

 deeph^ striated, and of a dark green color. Broken across near 

 the base, the interior exhibits a spherical nodule of transparent 

 achroite the third of an inch in diameter. 



Some magnificent crystals of the kind indicated have been for 

 many years in possession of Dr. Hamlin and his father, who first 

 discovered the locality from whence they were obtained. Dr. 

 Hamlin has more recently thoroughly explored the locality and 

 investigated the character of its tourmalines, an account of which 

 he proposes to give us in a future essay on the subject. 



October IT. 

 The President, Dr. Ruschenberger, in the chair. 

 Nineteen members present. 



Remarks on Fossils from Oregon. — Prof. Leidy directed atten- 

 tion to some fossils, part of a collection from Oregon, submitted 

 to his examination by Rev. Thomas Condon, and indicated in the 

 Proceedings of October 18th, 1870. 



One of the fossils, a brain cast, or rather a cast of the interior 

 of the cranium of a large mammal, has about the same form and 

 size as that of the horse. The cerebral hemispheres are nearlj' as 

 much convoluted as in the latter, and measure about four and a 

 half inches in length and breadth. It may pertain to a large 

 tapiroid animal, though I suspect it belonged to an oreodont. 

 1872.] 



