Sfudies in Prohlematic Orgatiisms. 67 



are found not only in the same beds, but frequently on the 

 same slabs, as the fish ; so that all that has been said of the 

 one applies as a consequence equally to the other. 



The species that belong to this locality apparently come 

 closest to, more so than any others, actually living species, 

 and in general to those that grow in the temperate oceans. It 

 is only necessary to except the two species we have placed 

 with doubt in the genus Fucoidcs, under the names of Fucoides 

 discophorus and turbinatus and Fucoides agardhianus, which, 

 especially, approaches Caulerpa, and, in consequence, to a 

 genus belonging almost entirely to the equatorial or southern 

 oceans. 



2. The fossil Fuci discovered in the lignite of the island of 

 Aix, near- Rochelle, by M. Fleurian de Bellevue, and for the 

 knowledge of which I am indebted to that savant and to M. 

 d'Orbigny. The lignite in which they are found has been 

 indicated by my father as a type of the lower marine lignite 

 of the chalk.* It does not contain any other determinable 

 vegetables, except the leaves we describe in this memoir 

 under the name of Zosterites. They appear to be composed 

 almost entirely of these Fuci and of the stems of trees, among 

 which I have not seen up to the present those of Dicotylodons. 

 Besides the two species of Fucoides we describe in this 

 memoir, there were included the debris of a great many 

 species, too incomplete to be determined. 



3. The species of Fucoides found in the limestones of 

 Stonesfield, near Oxford, and of which M. Buckland has 

 willingly given me a very correct plan. The beds here 

 included belong, according to this celebrated geologist, to the 

 calcareous oolite of the Jura. These beds contain, besides 

 the Fucoides, plants that we have placed with Lycopodites,! 

 and portions of leaves very probably belonging to ferns. 

 These specimens of ferns, that I did not know of on the pub- 

 lication of my first work on fossil vegetables, occasion some 

 modification of the information I have given of the fossil 

 vegetables of the Jurassic limestone in which I had not then 

 found the ferns, and proved that these vegetables are found 

 again in the lower formations of the Coal terrane. The only 



'■■See the article " Lignite," in the Dictionnaire ties Sciences NaliireUfs. 

 \Lycopodtles bucklandi. Mem. du Mus., vol. viii. 



