1897.] MICROSCOPICAL JOURNAL. 235 



This sand is mainly composed of minute worn frag-ments 

 of molusks. In that received by the writer there occur a 

 considerable number of foraminifera, some quite perfect 

 but most of them much worn. On treating- the sand to 

 hydrochloric acid, so as to dissolve the calcareous mater- 

 ial, about 1-25 of the original bulk remained. This remain- 

 der is evidently chiefly composed of small, worn, sand 

 g-rains, derived from the volcanic rocks of the island ; it 

 contains a few, very few, marine diatoms. ■ 



Sands which emit sound when their particles are rubbed 

 tog-ether, as when trod upon, are not infrequent, and are 

 not confined to calcareous sands. The writer has noticed 

 them in the siliceous sands on the beach between one and 

 two miles south of Beach Haven, N. J. None of these 

 sands emit sounds when wet ; to do so they must always 

 be dry. They are locally called by various names, as 

 sonorous, sounding-, barking, musical, and a?olian sands. 

 Alexis A. Julien has written an elaborate paper upon 

 "Musical Sands." Lewis Woolman. 



Section of Chalcedony. — Silica, Si O2 , occurs in nature 

 mainly in two forms, (1) crystalline and anhydrous as 

 quartz, and (2) amorphous and hydrous as opal. Chalce- 

 dony is g-enerally described as a crypto-crystalline variet} 

 of quartz ; that is to say, while it is essentially crystalline 

 in structure, the individual crystals in the mass are too 

 small to be distinguishable. It is usually found forming- 

 crusts and lining cavities or cracks in rock, an.d is a sec- 

 ondary mineral formed by the deposition of silica in suc- 

 cessive layers, this taking place so rapidly that there is no 

 opportunity for the formation of distinct crystals of quartz. 

 No doubt in many cases the silica thus deposited is largely 

 gelatinous when first precipitated, but a crystallization 

 soon takes place, so that in the mineral as usually found 

 there is not very much opal in proportion to the crystallized 

 portion. The crystallization proceeds from centre in a 

 radial manner, so that the surface takes an irregularly 

 rounded form which is described as botryoidal or mam- 

 millary. Between these minute crystals there is generally 



