THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY, 



[SECOND SERIES.] 

 No. 53. MAY 1852. 



XXIX. — Sketch of a Classification of Recent Brachiopoda ; based 

 upon Internal Organization. By Thomas Davidson, Member 

 of the Geol. Soc. of France, &c. 



The numerous dredgings undertaken under different latitudes 

 and in deep as well as shallow seas, have shown that recent 

 Brachiopoda are more numerically abundant and varied in 

 generic and specific forms than we formerly supposed. The best 

 account of the species of this order is contained in the mono- 

 graph by Mr. G. B. Sowerby, published in his ' Thesaurus Con- 

 chyliorum/ 1846. In that work fifty-seven recent species are 

 described and arranged under five genera, viz. Lingula, Tere- 

 hratula, Orbicula, Crania and Thecidea. 



Of late years many other genera have been proposed, and in 

 a minute investigation of the interiors of all the species of Tere- 

 bratula, I found so much variation in the dispositions of the cal- 

 careous appendages, as to necessitate a complete subdivision 

 and re-arrangement of the shells usually associated under that 

 name. All the known and described species, with two or three 

 exceptions only, are to be found in the magnificent collection of 

 Mr. Cuming, who in the most obliging manner placed his spe- 

 cimens at my disposal for examination. I am also greatly in- 

 debted to Mr. Gray of the British Museum, and Prof. Forbes, for 

 the means of examining the animal of many genera and species ; 

 these investigations, undertaken along with Mr. Woodward of the 

 British Museum, have proved of great assistance in enabling us 

 to ascertain what relation the calcareous supports or appendages 

 bear to the soft parts of the animal, and more especially to the 

 arms, in the different genera. 



It is not the object however of this paper to give descriptions 

 and synonyms of the different species, which will be included in 

 the catalogue of Brachiopoda Mr. Gray is about to publish for 



Ann.^Mag.N,Hist.^ev.2. VoLix. 24 



