210 Mr.DelaBeche on theGeographicalDistribution of Organic 



Of Pterodactyles our knowledge is limited. Crocodiles seem 

 to have existed during the whole deposit of the oolite, and to 

 have been widely distributed ; the same may be said of the 

 Ichthyosaurus and the Plesiosaurus. Neither Pterodactyles, 

 Crocodiles, Ichthyosauri, nor Plesiosauri, have yet been ob- 

 served in the South of France. The Geosaurus has at pre- 

 sent only been noticed in the lias of Wurtemberg, and the 

 Megalosaurus in the Stonesfield slate, near Oxford, and in the 

 great oolite of Normandy*. Respecting Tortoises, Turtles, 

 and Fish, we do not possess information that can lead to any 

 useful conclusions. Insects are yet known only in the oolite 

 at Stonesfield. Polypifers occur in considerable abundance in 

 particular places, and, as it would appear, principally in the 

 oolite that has been thence named Coral rag, and in the upper 

 part of the great oolite, which has thence obtained the name 

 of Calcaire a Polypiers in Normandy. It has been imagined 

 that the coral rag is a constant rock in the oolitic series ; which 

 is supposing that during the deposition of the oolite there was 

 a time when the whole bottom of the sea was covered by an 

 universal coral reef, and that the same polypifers could exist 

 under various pressures of water; suppositions that are at 

 variance with the habits of existing polypifers. When poly- 

 pifers do however occur in any abundance, they have been 

 observed in the strata above noticed, in both cases accom- 

 panied by remains of the genera Clypeus and Cidaris. By re- 

 ference to the above lists, it will be also observed that several 

 shells are common to the coral rag and great oolite. The 

 Crinoidal remains contained in the oolite appear principally 

 Pentacrinites and Apiocrinites ; the former occurring abun- 

 dantly and widely distributed in the lias ; the latter in the great 

 oolite, or its accompanying beds, the cornbrash, forest mar- 

 ble, or Bradford clay. 



Of the Conchiferous and Molluscous remains entombed in 

 the oolite, 540 species have, according to the foregoing list, 

 been determined; of these 114 (more than one-fifth) are Am- 

 monites, which are not only abundant as species, but as in- 

 dividuals, so that some beds are almost wholly composed of 

 them. The great abundance of Ammonites and Belemnites 

 may be stated as a great characteristic of the oolitic series : they 

 are particularly numerous in the lias. 



As far as our knowledge of the organic characters of Euro- 

 pean rocks at present extends, the shells contained in the ooli- 



* Dr. Buckland informs me that in the year 1826 he recognised many 

 bones of the Megalosaurus in the museum of Besancon from the oolite of 

 that neighbourhood, 



tic 



