452 FOSSIL INVERTEBRATED ANIMALS. 



the environs of Paris, as at Grignon and Chaumont, depart- 

 ment of the Oise, the univalve shells are filled to the top with 

 shelly sand. This sand is frequently found loose, without any 

 adherence to the shell ; but in certain shells it is found petri- 

 fied in those turbinations of the spire which are most remote 

 from the aperture, although it is not so in this last part. 



In the Bahama Islands, in our own days, a stratum similar 

 to that of Dane has been found. The debris of bivalve shells 

 belonging to that part of the world have been found in speci- 

 mens of this stratum, with colours. There is an aggregation 

 of the bodies which compose it, but no petrifaction. 



Certain fragments, which probably come from the Mediter- 

 ranean, are composed of a very hard and cavernose limestone, 

 which impastes the valves of the little moulds or modioles of 

 the vermicularia, or serpulse, the interior of which has re- 

 mained empty, and invests in hke manner the debris of the 

 same testacea. On the exterior of these fragments are poly- 

 paria of different genera, serpulse, with some portions of coral, 

 and the lower valves of craniae. Other pieces, which are found 

 in the sea, on the coasts of the department of Calvados, are 

 composed of grains of quartzose sand, of shells, of moulds, 

 with their red colour above and mother-of-pearl inside, of 

 debris of balanse, of asterise, and other polyparia. As the 

 debris of marine bodies which are contained in these pieces, 

 and especially in the first, do not appear to differ in any thing 

 from those which are not fossil, we may believe that these 

 petrifactions are not so ancient as those which are found in the 

 strata of the earth. With respect to the polyparia found in 

 the second, they are strangers to our climate, and have been 

 detached from the cliffs on the sea-coast, and depend on the 

 stratum with polyparia in the neighbourhood of Caen, so that 

 even if it were well proved that those petrifactions are recent, 

 it is yet clear that they are composed of the debris of beings 

 which have existed at very remote periods. It is remarkable 

 that the first fragments, which we have just mentioned, are not 



