ON THE PAGODA STONE OF THE CHINESE. 401 



thus a considerable diversity in the comparative 

 length and breadth of individual specimens, which 

 might amount to a specific difference between them. 

 " Pagoda stone " is a generic name ; and any species 

 of Orthoceras, from which a good section could be 

 cut, would be called by that name. 



The shell has been replaced with greystone not 

 differing from the limestone in which it has been 

 imbedded, but in some places it is darkened, and 

 forms a blackish border; greystone also forms the 

 septa, and the chambers or air-cells are lined or 

 defined with a thread of calcite, which is not so 

 clear as the crystalline spar which fills most of 

 them. 



The siphuncle in the larger specimen* can be 

 traced to the apex by transmitted light, and in 

 passing through twelve of the chambers is black 

 or carbonised. 



The first or largest chamber (Plate VI., a 1), which 

 was occupied by the body of the animal, is 3J inches 

 in breadth or diameter, and 2 inches in depth, but 

 may have been a little larger; and is filled with 

 greystone similar to the imbedding limestone — that 

 is to say, it is filled with the same mud as that in 

 which the Orthoceras was deposited, and contains 

 some small shells or fragments which are seen in the 

 section. Most singularly, a small Ortlioceras was also 

 deposited when the large one lay probably half 

 imbedded in the mud, and drifted into this chamber 

 in such a way that its apex has touched or entered 

 the siphuncular orifice, and in such a position that 

 the small shell is in a straight line with the 

 siphuncle of the large one. The whole was after- 

 wards covered with mud; and now that a section 

 has been made showing the siphuncle (s) of the large 

 one, it displays also a similar section of the small 

 one, with its siphuncle, too, for about one-third of 

 its length. The chambers of the small one are also 



* This specimen has been presented to the Museum of the 

 University of Glasgow. 



