The Edinburgh New Philosophical Journal. 261 



they were less useful, as they increased the transparency to such an 

 extent as to destroy all light and shade, and also the outlines. But 

 such experiments were eminently successful with the cretaceous ani- 

 malcules, more especially when turpentine was employed ; and of this, 

 the hest kind is that obtained from the Pinus bakamea, and which is 

 known in the shops by the name of Canada balsam. The use of this 

 substance on finely divided dry chalk, particularly after heat had been 

 applied, distinctly afforded to the author a result which had previously 

 been obscure, viz. that the said chalk contains so vast a multitude of 

 microscopic, and hitherto unknown polythalamise, or nautilites, as they 

 have been termed, having a size of from l-24th to 1 -288th of a line, 

 that frequently there must be far above a million in each cubic inch, 

 and hence far above 10 millions in a pound of chalk. In the white 

 or yellow chalk of the north of Europe, the particles of a somewhat 

 crystalline nature, are equal to, if not greater in amount than, the 

 organic remains, according to the respective volumes of the mass ; but 

 in the chalk of southern Europe, these organisms, and their visible 

 fragments, greatly predominate ; and these consist, as it would seem, 

 exclusively of well preserved polythalamise. But when we spoke of a 

 million of polythalamise in every cubic inch, we include only those 

 which are well preserved, of which the fourth part of a cubic line, or 

 every 1-1 2th of a grain of chalk, can be ascertained to contain 150 to 

 200, which would be equal to 600 or 800 in each cubic line, about 

 1800 to 2400 in each grain, and from 1,036,000 to 1,382,400 in every 

 cubic inch. 



" Besides the polythalamic cretaceous animalcules, siliceous infusoria 

 have been found in chalk at Gravesend, near London.* Professor 

 Ehrenberg has also found the cretaceous animalcules in the polishing- 

 slate from Oran in Africa (tertiary marl, according to Rozet), and 

 in the polishing-slate of Zante; and it has been discovered by him, 

 that even the chalk-marl of Sicily, which there forms whole ranges 

 of hills, and which Friedrich Hoffmann recognised as a member of the 

 chalk series, is composed of extremely well preserved siliceous infusoria, 

 including several of the characteristic chalk animalcules. He likewise 

 recognised three specimens of similar chalk-marl, composed of infusory 

 animals, or calcareous polishing-slate, among Greek minerals brought 

 by Mr. Fiedler ; and it has been ascertained that many of the siliceous 

 infusory animals of the chalk-marl of Sicily, Oran, Zante, and Greece, 

 are identically the same, and at the same time do not occur in other 



* In the flints of that locality the author also saw distinct scales of fishes, first of all 

 in the collection of Mr. Bowerbank of London ; but he afterwards himself found similar 

 specimens, which he carried home with him. 



