Ixviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



them : the result is, that some authors refer the whole formation, in- 

 cluding the Jurassic forms, to the Carboniferous epoch, whilst others 

 refer the whole, including the vegetable remains, to the Jurassic 

 period, accordingly as they attach a greater or less importance to the 

 evidence of Plants or of Mollusca. 



MM. Scipion Gras, Chamousset, Ewald, and Michelin refer the 

 whole to the coal-measures, whilst MM. Elie de Beaumont, Ad. Bron- 

 gniart, De la Beche, De Montalembert, Bertrand-Geslin, Sismonda, 

 Dufrenoy, De Collegno, and Roget (1855) consider the whole as be- 

 longing to the Jurassic period. The weight of evidence appears to 

 be in favour of referring the whole formation to the Jurassic rather 

 than to the Carboniferous period. 



M. Barrande has also published in the Bulletin* a memoir on the 

 organic filling-up of the siphuncle in some of the Palseozoic Cepha- 

 lopoda. This phaenomenon was first incidentally noticed by the 

 author in the Orthoceratites of the family Vaginati. Further re- 

 searches showed that these were not the only creatures possessing 

 the faculty of secreting an organic substance, for the purpose of suc- 

 cessively closing up the space of the siphuncle. An examination of 

 all the ancient Cephalopoda, and particularly the Nautilides, led the 

 author to the discovery that the gradual closing up of the siphuncles 

 takes place, not only in the other groups of the genus Orthoceras, 

 but also in the allied genera of Cyrtoceras, Phragmoceras, and Gom- 

 phoceras, &c., and, generally speaking, in all the Nautilides with a 

 large siphuncle ; whilst no certain trace of it could be found in those 

 with a narrow siphuncle. The importance of this discovery, both in a 

 zoological as well as in a palseontological point of view, has induced 

 the author to publish the result of his investigations. After descri- 

 bing the different modes in which this closing up of the siphuncles 

 takes place in different groups of Cephalopoda, with particular re- 

 ference, however, to the various families of Orthoceras, the author 

 concludes with some general observations respecting the object of 

 this phaenomenon, and observes, that the study of it leads to results 

 which confirm former opinions respecting the vertical distribution of 

 the Cephalopoda in the Palaeozoic formations, and will hereafter 

 further tend to establish a correct geological chronology of these old 

 sedimentary deposits. 



M. Jules Haime has communicated to the Academy of Sciences an 

 account of the Geology of the Island of Majorca. The oldest beds 

 he has described belong to the upper and middle groups of the 

 Liassic formation. They contain many characteristic fossils, as Be- 

 lemnites umbilicatus. Ammonites Jamesoni, Maciromya Hasina, Pho- 

 ladomya decora, Lima pectinoides, Pecten, Rhynchonella tetrahedray 

 &c. He also found Oxford clay with Ammonites plicatilis and 

 A. athleta, Belemnites hastata, and Terehratula diphya. The Neo- 

 comian formation has also a great development in this island, with 

 its characteristic fossils. Above this are beds of the Cretaceous epoch, 

 overlaid by others containing Nummulites. This again is overlaid 



* Vol. xii. p. 441. 



