LAMARCK. 



About the year 1787, in the Nova Testaceornm Genera 

 Retzius proposes to add three genera to the Linnaean ones 

 which is stated to be according to the intentions of Linneeus 

 as communicated to him by Acharius-f : 1st, Perna, which in 

 eludes Mya Perna and some species of Mytilus -^ 2dly, Unio 

 consisting of Mya Pictorum and margaritifera ; and 3dly, Me^ 

 Una, of Ostrea semi-aurita, Perna Isogonum, and Ephippiian. 

 He also proposes to divide the genus Anomia into four, viz 

 Anoinia, Crania, Terebratnla, and Placenta. Most of these 

 genera have since been adopted by M. Lamarck. 



Considering the number of shells that have been already col- 

 lected fi'om all parts of the world, and which have not yet found 

 their proper places in the system, from their not perfectly agree- 

 ing with any of the genera already established, the necessity 

 of improving the Linnaean system, by increasing the number 

 of genera and rendering them more definite, becomes every 

 day more apparent. Something of this sort has been lately 

 attempted in France by M. Lamarck (who enjoys the advan- 

 tage of free access to the National Museuni of Natural History 

 at Paris) in his Systeme des Animaiix sans Vertehres, and in 

 his other writings. 



M. Lamarck's arrangement has been followed in this coim- 

 tiy by Mr. Parkinson, in his description of fossil shells, in 

 the third volume of Organic Remains of a Former World, in 



* Linn. Trans, vol. 7. p. 204. t Ibid. 



