Scientific Intelligence — Geology. 375 



discovery entirely new, for which we are indebted to M. Ehren- 

 berg, and which he has demonstrated to me in the clearest man- 

 ner ; it is, that the rocks of homogeneous appearance, which are 

 not very hard, friable, even fissile, entirely formed of silex, and 

 which are known by the name of tripoli, more or less solid 

 (Polierschiefer of Werner), are entirely composed of the exuviae, 

 or rather of the perfectly ascertained skeletons of infusorial ani- 

 mals of the family of the BacillaricB, and of the genera Cocco- 

 nema, Gornphonema, Synedra^ Gaillonella, &c. These remains 

 having perfectly preserved the forms of the siliceous carcasses of 

 these infusoria, may be seen with the greatest clearness through 

 the microscope, and may easily be compared with living species, 

 observed and accurately drawn by M . Ehrenberg. In many 

 cases there are no appreciable distinctions. The species are dis- 

 tinguished by the form, and still more surely by the number of 

 septa or transverse lines which divide their small body ; and M. 

 Ehrenberg, who has been able to count them by the microscope, 

 has observed the same number of these divisions in living and 

 in fossil species. They are the tripolis of Bilin in Bohemia, of 

 Santa-Foria in Tuscany, and of other places which I do not 

 remember with certainty (of the Isle of France, and of Francis- 

 bad, near Eger, if I am not mistaken), which had given occa- 

 sion to these curious observations. The slimy iron-ore of marshes 

 is almost wholly composed of Gaillonella ferruginea. The 

 greater part of these species are lacustrine, but there are also 

 some marine, particularly in the tripoli of the Isle of France.'"* 



— V Institute No. 166. Professor Jameson and Mr Nicol 



have examined carefully characteristic specimens of polishing- 

 slate (Polierschiefer), and found in them numerous remains of 

 lacustrine infusoria, thus confirming the discovery of Ehrenberg, 

 in so far as it applies to the Polier-slate. 



11. Dinotherium giganteum. — It is said there has been lately 

 found in the neighbourhood of Eppelsheim, at a depth of 28 

 feet, the head of the Dinotherium giganteum, the most colossal 

 fossil quadruped hitherto discovered. The head is in a state of 

 complete preservation ; it measures 6 feet 3^ inches (French) in 

 its greatest length, and it weighs about 500 pounds. There 

 was found near to this head a humeral bone six feet long, which 

 was considered to belong to the same animal. 



