THE OOLITIC ECHINODERMATA. 435 



wliicli are found in older formations ; with the deposition of the Cornbrash the lower 

 division of the Oolites terminate, and with that formation all the species of Echinodermata 

 found in these rocks became extinct. 



The middle division of the Oolites contains far fewer species than the lower. The 

 Kelloway rock and Oxford clay, so rich in Cephalopoda, have not in England, as far as T 

 can learn, yielded any remains of Echinodermata. The Lower Calcareous grit, Coral 

 rag, and Upper Calcareous grit, have several species in common ; of the eleven species of 

 the Lower Calcareous grit, six are common to it and the Coral rag, which contains twenty- 

 four species ; I have not ascertained how many, if any, pass into the Upper Calcareous 

 grit ; in fact, these three stages represent in reality only one stratigraphical zone of life. 



The Kimraeridge clay up to the present time is known to contain only four species, 

 which are all special to it. There is one species in the Portland sand, one in the Portland 

 Oolite, and one in the Marine Purbeck beds. The Portland Oolitic limestone is said to 

 contain the remains of several Echinoderms, although I have been able to obtain only 

 two specimens of the same species for examination from that formation. 



