n 



contained either some organism, or had been 

 formed on some organic substances, such as 

 sponge, coral, wood, shell, &c. Occasionally 

 they were found hollow ; in such cases, the organic 

 substance had decomposed, and its place had be- 

 come partially occupied by agate, chalcedony, or 

 crystalized quartz. The microscopic examination 

 of thin sections, or chippings of flints, revealed 

 the presence of foraminifera, sponge spicules, 

 xanthidia (believed by some to be Sporangia of 

 Desmidiae), and other minute forms of organic 

 life. Several theories have been promulgated 

 respecting the way in which flint was formed : 

 some leaning to the opinion that soluble silicates 

 infiltrated or deposited themselves on organisms ; 

 while others considered that silex was simply 

 held in solution, and then deposited. Analogues 

 of flint formation were seen in the Beekites of 

 the Torbay conglomerate, the so-called potato- 

 stones of Bristol, &c. That silica could be held 

 in solution was proved by the Geysers of Ice- 

 land and the waters of the Danube ; while 

 the fluid glass of the chemist showed the 

 readiness with which silex combined with an 

 alkali, and became soluble. Some thought that, 

 at the bottom of the Atlantic Ocean, flint was 

 being formed at the present time. Animals and 

 plants possessed the power of taking up silex, 

 as seen in the spicules of sponges, the lovely 

 Hyalonema and Euplectella, the cuticles of many 

 plants, the Diatomaceae, &c. The application of 

 flint to economic purposes in the past and 

 present was also pointed out, while the paper 

 was illustrated by a large collection of flints, 

 contributed by the President, Mr. Glaisyer, and 

 Messrs. Wonfor, Peto, and Scott. 



