40 



THE GEOLOGIST. 



divisions, and therefore if there exist three chief divisions in the Kimnie- 

 ridien formation, the limits of these groups are very different from those 

 which have been assigned to them. 



These are the opinions Dr. Contejean has striven to work out in the 

 book before us, and to this end he first describes the geographical range of 

 the Kimmeridge beds, through Damvant, Abbevillers, Audincourt, Mont- 

 beliard, and Belfort, in a north-westerly direction ; then through the Allan 

 Valley to the district of Ponentruy ; and next, south-westwards, to Long- 

 velle and l'lle-sur-le-Doubs. He then describes the subdivisions, with 

 their mineral characters and their characteristic fossils. These subdivisions 

 are : — (1) Calcaire a Astartes ; (2) Calcaire a Natices; (3) Marnes a 

 Astartes ; (4) Calcaires a Terebratules ; (5) Calcaire a Cardium ; (6) Cal- 

 caires et Marnes a Pteroceres ; (7) Calcaire a Corbis ; (8) Calcaires a 

 Mactres ; (9) Calcaires et Marnes a Virguhs ; (10) Calcaire a Diceras. 



A section of his book is now devoted to detailed lists of the respective 

 faunas of each of these subdivisions, and to comments upon them. After 

 a summary of the facts thus brought forward, he tabulates his results in 

 the following manner : — 



Etage Kimmeridien. 



IV. Groupe JN"erineen . Subdivisions to be made out. 



10. s. gr. Calcaire a Diceras. 

 9. Calcaires et Marnes a Vir gules. 

 8. Calcaire a Mactres. 

 7. Calcaire a Corbis, 

 f 6. Calcaires et Marnes a Pteroceras. 

 II. Groupe Pteeocerien ( 5. Calcaire a Cardium. 



I 4. Calcaire a Terebratules. 

 f 3. Marnes a Astartes. 

 I. Groupe Astartien . ( 2. Calcaire a Natic-es. 



{ L Calcaire a Astartes. 



The last question then remains — what are the limits of the Kimmeridien 

 as thus defined? These Dr. Contejean asserts are exactly indicated. The 

 Kimmeridge division terminates the Jurassic marine series, and is naturally 

 arrested by the Purbeck beds, which most geologists have considered 

 cretaceous, but which the author considers M. Coquand has rightly asso- 

 ciated with the Jurassic formation. The inferior limits he sets forth as 

 equally easy to establish, the Kimmeridge division commencing where 

 the mass of fossil corals ends, or immediately above the Diceras beds of 

 the Coralline Oolite. 



The fourth section of his work Dr. Contejean devotes to the " Parallel- 

 ism of the Formation," and notices the characters presented in the Medi- 

 terranean basin, Straits of Dijon, Anglo-Parisian basin, and the Pyrenean 

 basin. This is followed by a fifth portion, with geological sections and a 

 general list of the fossils of the whole formation. The remainder of the 

 book, amounting to a hundred pages, is taken up with detailed descriptions 

 of new or critical species of shells, which are illustrated by twenty-four ad- 

 mirable lithographed plates, very carefully and accurately drawn. The 

 book is moreover illustrated by three plates of sections and stratigraphical 

 diagrams of the ranges of the various groups of fossils. 



We have, in former reviews, Itad occasion to speak well of the geological 

 works published by M. Eothschild, but of none we have yet noticed could 

 we desire to speak in higher terms of praise than of Dr. Contejean's admi- 

 rable monograph before us. 



III. Groupe Viegulien 



