Prof. Ehrenberg's Notices regarding Fossil Infusoria. 85 



A highly interesting specimen of polishing slate, from Cassel, 

 was sent me by Carus of Dresden, in which he also had detect- 

 ed the existence of organic forms. From the same locality there 

 are also specimens in the Royal Museum, some of them contain- 

 ing remains of the fish called Leuciscus papyraceus, Bronn. Very 

 recently, through the kindness of Mr Keferstein of Halle, I have 

 been enabled to examine other specimens of the Cassel polishing 

 slate from Habichtswalde. This polishing slate of Casscl con- 

 tains seven different species of loricated infusoria, between whose 

 remains there occurs a loose, chiefly siliceous cement, which 

 cannot be clearly reduced to remains of organic beings. The 

 most remarkable circumstance is, that, while in the Bilin and 

 Planitz polishing slate, most of the forms are those of animals 

 which are extinct, or which have not yet been discovered in a 

 recent condition, and the forms which resemble living species 

 belong to those which are not well characterized, and are hence 

 less fitted for ascertaining the identity; there occur, on the con- 

 trary, in the Cassel polishing slate two of the best characterized 

 of the living forms, viz. the Gaillonella varians, and Navicula 

 viridis. The Navicula striatula seems also to occur. The 

 Gaillonella varians and the Navicula viridis are common to the 

 tertiary formation of Cassel and the Bergmehl of Santa Fiora, 

 and both these deposits contain a form analogous to the Navicula 

 Follis. Besides 1 Gaillonella varians, 2 Navicula viridis, 3 

 Navicula striatula ?, 4 Navicula crux (N. Follis adulta) ; I 

 also found in the Cassei rock, 5 Navicula Julvajuv. ?, 6 Na- 

 vicula gracilis ? , and 7 Navicula Cari 9 n. sp. ; three species that 

 are less distinctly marked, but of which the last is extremely 

 abundant, and is new to me. 



Besides these facts, which have been ascertained regarding the 

 distribution of the infusory slate in the form of polishing slate, 

 the valuable collection from Bilin, and the valley of Luschitz, 

 sent by Humboldt, has given rise to some very fortunate inves- 

 tigations. The series of specimens consisted of a small collec- 

 tion of Bilin minerals from Dr Stolz of Bilin, a larger collec- 

 tion from Dr Reuss, besides many fragments obtained by Hum- 

 boldt himself. A carefully executed sketch by Dr Reuss, ex- 

 plains the arrangement of the rocks. 



The Bilin infusory rock is about fourteen feet in thickness, 



