Zoological Society. 145 



PROCEEDINGS OF LEARNED SOCIETIES. 



ZOOLOGICAL SOCIETY. 



May 25, 1852.— J. Gould, Esq., F.R.S., Vice-President, in the Chair. 



Descriptions of a few new recent species of Brachio- 

 PODA. By Th. Davidson, F.G.S., Member of the Geol. 

 Soc. OF France, etc. 



In the valuable collection of recent Brachiopoda assembled by Mr. 

 Cuming, some species seem new, and undescribed in Mr. Sowerby's 

 Monograph ; and it is at that gentleman's request that I have pre- 

 pared the following descriptions, which will complete, with one ex- 

 ception, the Ter. septigera of Loven (still unfigured), all the new 

 recent forms which have hitherto come under my observation. 



In a paper published in the * Annals and Magazine of Nat. Hist.' 

 for May IH52, I endeavoured to class all the recent species according 

 to their internal organization, mto four families and thirteen genera, 

 or sections, as it is evident that these, as well as the fossil forms, must 

 be comprised in the proposed subdivisions introduced within the last 

 few years with more or less success into the nomenclature ; and sin- 

 gular enough, notwithstanding the greater facilities of examining both 

 the internal arrangements as well as the animal in recent forms, these 

 important characters have not yet been made use of by malacologists, 

 who still place nearly all these Terebratulitbrm shells in one genus, 

 Terebratula ; while palaeontologists, working under much greater 

 difficulties, have by dint of perseverance and trouble discovered the 

 organization of a multitude of extinct forms, filled by the hardest 

 matiix : and I have no doubt but that before very many years the 

 internal details of all the fossil species will be as well known as if they 

 were in the recent state. 



Much, however, remains to be done before the proposed classifi- 

 cations can be decidedly and definitely adopted, and many modifica- 

 tions will be considered requisite, as it is evident, from our present 

 knowledge, that some genera or sections are more or less closely re- 

 lated, and that certain species possess characters common to more 

 than one genus, but these examples are few and exceptional in com- 

 parison to those presenting a similar organization : thus all forms 

 with a free, simply attached loop, as in Ter. Australis, Ter. Calif or- 

 niana, &c., must be placed in the same section ; all those with the 

 loop affixed to the hinge plate and to a central more or less elevated 

 septum, such as Ter. dorsata, Ter. rubicunda,kc., into another group ; 

 those also in which the calcareous appendages consist of only two cen- 

 tral diverging lamellae, such as Ter. rubra, Ter. pisum, and others, 

 must necessarily be placed close to each other, &;c. The arrange- 

 ment of the species is, therefore, not a matter of indifference, but 

 ought to partake of those rules, followed for the other classes of Mol- 

 lusca, wherein genera are often admitted on far less important differ- 

 ences. 



A complete monograph of the recent species thus framed, with 

 Ann. ^ Mag. N. Hist. Ser. 2. IW. xiv. 10 



