[ 442 ] 



LXIV. Reply to some Remarks of Prof. A. Leymerie on the 



Identification of certain Loxioer Greensand Fossils. By Prof. 

 Edward Forbes, F.R.S., of King's College^ London. 



To Richard Taylor, Esq. 

 Dear Sir, 

 T N the last Number of the Philosophical Magazine appears 

 -■- a translation of a paper read before the Geological So- 

 ciety of France, by Prof. A. Leymerie, and entitled " Obser- 

 vations on a Communication made by Dr. Fitton to the Geo- 

 logical Society of France at the Meeting of May 20, 1844, on 

 the Lower Greensand of the Isle of Wight," read November 

 4, 1844, and published in the Bulletin of the French Geolo- 

 gical Society for January 1845. 



In that paper M. Leymerie is rather severe upon me and 

 my palaeontological determinations, unreasonably, as I con- 

 ceive, and I hope you will permit me to reply through the 

 medium of the Philosophical Magazine. I am the more 

 anxious to do so, in order to prove to my geological friends 

 that I do not deserve the accusations of hastiness and careless- 

 ness preferred against me by M. Leymerie, and that I did not 

 draw up the lists of Lower Greensand fossils for Dr. Fitton and 

 other English geologists interested in the Neocomian question, 

 without full and due consideration and good materials before 

 me. 



Fortunately the accusations are more special than general. 

 M. Leymerie has fully stated the grounds of his doubts. At 

 once, then, I will go over separately the list of species (eight 

 in number) which forms the text of the lesson he would read 

 me. 



The first is ^^ Pholadomya Prevosti^ Desiiayes," identified by 

 me with Mya plicata, Sowerby — wrongly according to M. 

 Leymerie, who adds, moreover, on M. Deshayes' authority, 

 that the species of Sowerby is a Panopaa, whilst the French 

 shell is a Pholadomya. 



I identified the English fossil, which certainly is the species 

 of the Mineral Conchology, with the French for the following 

 reasons : — 1st. One of the commonest varieties of the Lower 

 Greensand, Panopwa plicata^ exactly agrees with the figure 

 and description given by M. Deshayes in M. Leymerie's paper 

 on the Cretaceous Formation of I'Aube. 2nd. Specimens of 

 the English shell sent to France were returned as P. Prevosti 

 by M. d'Orbigny. 3rd. Specimens of the French shell 

 brought to England were compared by myself with our own 

 specimens, and found to be identical. As to the genus to 

 which both English and French shells belong, there can now 



