SUPPLEMENTARY NOTES. 461 



the Porphyry of Kaschau. In the white and opake bands of a few 

 chalk Hints, he has also found spherical and needle-shaped micro- 

 scopic bodies, which he considers to be of organic origin; these 

 are most abundant in the white siliceous crust which forms the 

 exterior of the flints, and in the mealy siliceous powder sometimes 

 found within their cavities, but are not distinguishable in the black 

 interior of the nodule. The existence of living marine species 

 of Infusoria, renders it probable that animals of this class 

 existed also in the early seas in which the stratified rocks were 

 deposited. The fact that living Infusoria have the power of se- 

 creting Silex and Iron, places their fossil siliceous and ferruginous 

 remains, nearly in the same category with the fossil calcareous 

 exuviffi of Foraminifers, Polypes and Crustaceans. 



The living species of these animalcules, which are now begin- 

 ning to be found so abundantly in a fossil state, are divided into 

 two classes and six families ; three of these families have a naked 

 flexible epidermis, and three, a siliceous epidermis, forming a trans- 

 parent shell, or cuirass. The cuirass, in the greater number of 

 species, is composed of two siliceous valves, the univalve cuirass 

 has the shape of a leaf, with its edges rolled inwards towards each 

 other. About one half of Ehrenberg's genera of Infusoria, have a 

 siliceous cuirass, and the other half, a membranous covering. 



The species found at Carlsbad do not live in the rising thermal 

 water, but are seen a small distance from the spring, covering the 

 stones and wood with a green slimy substance, chiefly composed 

 of the bodies of millions of Infusoria. These animalcules are never 

 found in the rising water of a hot spring, nor in the limpid water 

 of a cold spring, river, or well. 



P. 3.37, Note. Mr. Searles Wood has discovered fifty species 

 of foraminifers in the lower Crag formation of Suflx)lk. 



Lond. and Edin. Phil. Mag. Aug. 1835. p. 86. 



P. 371. Mr. Webster was the first who noticed in the I. of 

 Portland the interesting Phenomena of the Bed of black vegetable 

 mould called the Dirt Bed, with its fossil wood, pebbles, &c. and 

 ascertained that the silicified Trees found in this island had been 

 obtained from this bed only, and not from the Portland Oolite. 



39* 



