Remains in the Oolite Series of England and France. 89 



many fossils, lead us to assimilate these beds with those named 

 Coral Ra'r by the English, and the oolite which accompanies 

 them to t1ie Oxford oolite. These are the only two subdivi- 

 sions which can be made in the middle group, and even these 

 so pass into each other that, at the Pointe d'Angoulin and 

 Marthon, numerous polypiiers are found in the midst ot the 

 oolite beds. Beds of very marly limestone cover this system. 

 We already find some of the Gryphsea virgula, the presence 

 of which with us (France), characterises the clay separating 

 this system from the upper. This group of the oolite covers 

 a space about two leagues and a half broad between La Ko- 

 chelle and Rochefort ; it is more considerable between Poitiers 

 and Angouleme, and between the last town and Contolens. 



" The upper system is the most uniform in this basm ; it is 

 often reduced to a few marly beds, containing a prodigious 

 quantity of the Gryphsea virgula, attached to one another, and 

 nearly forming by themselves a bed of lumachella. In some 

 localities this is covered by compact marly limestone forming 

 very thick beds (Cahors), in which this little gryphite, so cha- 

 racteristic in France, is found here and there disseminated. 

 From the environs of Angouleme to the ocean, beds ot oolite 

 are observed nearly constantly to cover these marls containing 

 the Gryphaea virgula; they reappear in other places (Pointe 

 du Rocher), and are immediately in contact with the green- 

 sand. By comparing this system with that which exists in 

 Enrrland, we may assimilate the oolite of which we have spoken 

 with the Portland stone, while the lower beds of marl, con- 

 taining the Gryphsea virgula, correspond with the Kimmeridge 

 clfiv 



The reader being now in possession of what maybe termed 

 the mineralogical character of the oolitic series at the various 

 places above noticed, I shall proceed to examine the organic 

 character of the same series derived from the same authorities, 

 commencing with the inferior system. 



♦ Formations Jurassiques du Sud-ouest de la France. — /fn«a/« Jes 

 Mines, torn. v. p. 4.30—434. 



N.S. \i>\. 7. No. fiH, Feb. ISaO. N Organic 



