Ch. XVIL] 



OF SOUTH OF EUROPE. 



337 



are met with in the chalk of the north of France, are scarcely ever 

 found in the southern region ; while the genera Ilamite, Turrilite, 

 and Scaphite, and perhaps Belemnite,ave entirely wanting. 



On the other hand, certain forms are common in the south which 

 are rare or wholly unknown in the north of France. Among these 

 may he mentioned many Hippurites, Sphcerulites, and other members 

 of that great family of mollusca called Budistes by Lamarck, to which 

 nothing analogous has been discovered in the living creation, but 

 which is quite characteristic of rocks of the Cretaceous era in the 



Fia 327. 



Fiar. 



m 



a. Enuolites radiosa, D'Orb. 

 Z>. Upper valve of same, 



White chalk of France. 



Eacliolites foliaceus, D'Orb. 



Syn. Sphcerulites agarici- 



formis, Blainv. 



White chalk of France. 



Fiar. 329. 



Eippuriiea organisans, Dcsmoulins. 

 Upper chalk :— chalk marl of Pyrenees ? * 



a. Young individual ; when fall grown they occur in groups adhering 



laterally to each other. 



b. Upper side of the upper valve, showing a reticulated structure ir 



those parts, &, where the external coating is worn off. 



c. Upper end or opening of the lower and cylindrical valve. 



d. Cast of the interior of the lower conical valve. 



* D'Orbigny's Paleontologie Fran^aise, pi. 533. 

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