EXPLANATION OF THE PLATES 



Plate 8. Fossil organic remains of the marl beds of 

 the compact Jura limestone. 



Fig. 1. Strombus Pelagi. A. Br. 



A and C. The same individual seen on different sides. 

 B. Another imperfect individual, furnished with tubercles 

 on the edge of the lip ; they appear to indicate the bases of 

 spines terminating this lip in the adult individuals. 



The dotted lines represent those parts that are supposed 

 to be wanting : it bears some resemblance to Strombus 

 Gallus. (Coll. of Deluc.) 



Fig. 2. Strombus Oceani. A. Br. 



A. An individual apparently adult and complete, B. A 

 younger individual. 



Fig. 3. Strombus Ponti. A. Br. 



A. An imperfect individual, but in good condition. 

 B. An individual which appears imperfect, but which is 

 worn. 



The'se strombi are interior casts. The shell does not 

 remain on any one. I have not found them either figured, 

 described, or even noticed in any general work that I have 

 been able to consult. 



Fig. 4. A. B. Lutraria ? Jurassi. A. Br. 



The genus can only be presumed from the form, the. hinge 

 not having been as yet observed. This species does not 

 appear to me to have been described or at least distinguished. 

 It bears some resemblance to the mactra gibbosa of Sowerby^ 

 which is a Lutraria. 



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