PREPARATION OF THE DIATOMACE^. 141 



is difficult to obtain. On the island of Jutland, in Denmark, is 

 found a series of polishing slates, the polischeifer of the German 

 geologists, containing Trinacria regi?ia, which is quite local in its 

 origin, and also Coscinodisciis ociilis-iridis^ both very abundant in 

 the Fiir Rock; and it is also remarkable that the latter 

 approaches in character, somewhat, the diatoms of the London clay. 

 These were discovered some httle time since by W. H. Shrubsole, 

 Esq., F.G.S. The silica of the frustules has been replaced by iron 

 pyrites, thus giving them, by reflected light, the appearance of 

 brass buttons. I strongly recommend that these should find a 

 place in every cabinet, and as Mr. Shrubsole informs me his 

 supply is exhausted, he has advised me to apply to Mr. A. C. Cole, 

 of London, with whose " Studies " we are all so well acquainted. 



Another well-known deposit is that of Oran, in Algeria, which 

 abounds in some of the smaller forms of Coscinodisciis^ as 

 well as Dictyocha fibula. ^Egina and Caltanisetta, in Greece, 

 furnish us with similar forms, intermixed with Polycystina and 

 Foraminifera, evidently of the cretaceous age. The Springfield 

 deposit also is justly celebrated for the variety and beauty of its 

 Polycystina ; and these are accompanied by forms of Diatom- 

 acese which are by no means less interesting. 



Indeed, I might add that as there are so many localities which 

 furnish these, it is very probable that the whole of the island of 

 Barbadoes is occupied by one deep stratum of chalk marl. A 

 similar deposit has been discovered in the Island of Trinidad, 

 which is considered to be connected with the New Red Sandstone 

 series. At Moron, in Spain, the same stratum again occurs ; and 

 a still further deposit was discovered by Dr. C. F. Winslow at a 

 point about seventy miles south of the town of Payta, in Peru, 

 on a broad plain, having various depressions, the bottom of which 

 w^ould correspond with the ordinary sea level. The surface 

 of the soil is covered with salt to the depth of about fifteen 

 feet ; recent sea-shells are next met with, then the bones of certain 

 cetaceans mixed with pebbles ; then for one or two feet follows 

 a yellow loam ; and last of all the stratum containing the diatom- 

 aceae, which consists of a thickness of from two to four feet. A 

 similar deposit also occurs at Tetani, in Japan, and is certainly 

 one of our most interesting series, from its comparative rarity and 



