Mr. T. Davidson on the Bi'achiopoda. 429 



to Rissoa, are derived from an observation of Loven, who did 

 not, however, regard them as species of those genera, but only 

 intended to show that an affinity existed between them, as far 

 as the outer form of the animal was concerned. 

 I am, Gentlemen, 



Your obedient Servant, 



J. E. Gbay. 



XXXVI. — Afeiv Remarks on the Brachiopoda. 

 By Thomas Davidson, Esq., F.G.S. &c. 



[With a Plate.] 



1 . On the Systematic Arrangement of Recent and Fossil 

 Brachiopoda. 



Shortly after the publication of the General Introduction to my 

 work on 'British Fossil Brachiopoda,^ to which Prof. Owen 

 and Dr. Carpenter each contributed most valuable chapters, 

 M. Deslongchamps and his son proposed to make a French 

 translation of the third chapter treating especially of Classi- 

 Jication, which the Linnsean Society of Normandy had in the 

 most liberal manner offered to publish in the tenth volume of 

 their Transactions. About the same period I received a similar 

 offer from M. Suess and Count Marschall of Vienna with respect 

 to a German translation. But although highly flattered by such 

 liberal propositions, I felt that much could be done to improve 

 the original by corrections, as well as by considerable addi- 

 tions, both in text and illustrations. I therefore entirely revised 

 my English work, printed in 1853, before it went through the 

 process of translation, and owing to the exertions of my friends, 

 I am happy to say that both editions are now printed, and I 

 trust will be ready for issue by the end of the present year. 



As stated in my English work, we are not yet in a condition 

 to offer a really complete and permanent classification of the 

 numerous species composing the class ; for to be able to do so 

 effectually, one would require to be still better acquainted with 

 the recent animals as well as with the interior of many obscure 

 fossil species ; and it is therefore of the greatest importance not 

 to allow ourselves to be led into proposing genera or subgenera 

 on trifling modifications or unimportant details which exist only 

 in certain abnormal forms*. 



* For example, the genus Seminula (M'Coy) is founded on the more 

 developed state of the dental plates, while otherwise the shells in question 

 possess all the essential characters of Lhwyd's original genus Terebratula. 



