1883. 21 Trans. N. V. Ac. Set. 



the flagging of the streets of that city, and were supposed to have 

 fallen from the atmosphere. 



The President stated that these shells belonged to the species 

 Bulimus lubricus, called by Binney Feriocyclea. This shell was 

 very widely disseminated throughout the country and abroad. It 

 had not rained down, as suggested, but had probably multiplied to 

 an unusual degree during the past summer, and was " swarming," 

 as lemmings, butterflies, and other animals do ; a mysterious mi- 

 gration, perhaps to escape over-crowding and the exhaustion of 

 food, 



Mr. G. F. KuNZ exhibited several remarkable specimens of Bra- 

 zilian diamonds. Some were perfect spheres, one being of the size of 

 a child's marble, and weighing over forty carats, d.T, grammes (spe- 

 cific gravity, 3.5195). The latter consisted of a conglomerated mass 

 of cubes, so bunched together as to have lost all crystalline form. 

 The same bunching of crystals was illustrated by a spherical mass 

 of common pyrite, and in others which revealed traces of crystal- 

 line form. This spherical shape was never produced in the 

 diamond by rolling in streams. Another diamond of black color, 

 weighing 1.2 gramme (sp. gr., 3.649) revealed no trace of crystalline 

 form, perfectly amorphous. Another of gray color, weighing 1.6 

 gramme (sp. gr., 3.522), was also a vitreous mass, in which scarcely 

 any crystalline form was apparent ; this was also the character of 

 a milky diamond exhibited, weighing i.i gramme (sp. gr., 3.522). 

 One diamond, weighing over 6 carats, presented a table and culet, 

 in which each alternate facet (eight on top), as well as the centre, 

 was white, and all the other facets were a deep black. This was 

 originally a white octahedron with a black coating ; the slicing off 

 of the four angles had produced the white faces. A crystal of 

 South* African diamond exhibited on an artificial surface of cleav- 

 age, the projection of the perfect four faces of an enclosed octa- 

 hedron of the same mineral, with the corresponding impression of 

 these faces in the slice cleaved off. A cut ruby from Siam was 

 also exhibited, that enclosed a perfect octahedral crystal of ruby- 

 colored spinel, about two millimeters in length. This inclusion 

 hod been considered, by the owner of the gem, as a serious im- 

 perfection, requiring removal, although it really added much to 

 its interest and value, and the gem was in this case truly a ruby 

 spinel. 



