L 547 ] 



XXVI. Researches on the Foraminifera. 

 By WILLIAM B. CARPENTER, M.D., F.R.S., F.G.S. $c. 



Received June 19, Read June 19, 1856. 



PART II. 

 ON THE GENERA ORBICULINA, ALVEOLINA, CYCLOCLYPEUS AND HETEROSTEGINA. 



Genus ORBICULINA. 



78. History. X HE interesting group of organisms belonging to this type seems to 

 have early attracted notice, probably on account of the great abundance in which it 

 presents itself on the sands of many of the West Indian shores. Three species are 

 described and figured by FICHTEL and MOLL*, under the names of Nautilus orbiculus, 

 N. angulatus, and N. aduncus. LAMARCK, however, in his first systematic treatise-^-, 

 separated them from Nautilus, and raised them to the rank of an independent genus, 

 to which he gave the name of Orbiculina ; and he also changed two of the specific 

 names, the three standing respectively as O. numismalis, O.angulata, and O.uncinata. 

 By DENYS DE MONTFORT^:, these species were raised to the rank of independent 

 genera, under the names of Helenis, Archaias, and Jlotes ; but these genera have not 

 been adopted by any other systematise M. D'ORBIGNY^, in his first classification of 

 the Foraminifera, not merely adopted LAMARCK'S generic designation, but affirmed 

 that the three reputed species were really nothing else than one and the same organism 

 in different phases of growth, O. angulata being the youngest, O. numismalis the 

 next in age, and O. uncinata the .adult. He arrived at this result, of the truth of 

 which I am myself well assured, by the comparison of a great number of specimens, 

 a process which it would have been well for science if he had more constantly 

 adopted. The name of the adult form should of course stand as that of the species ; 

 but the organism in question is more commonly known under the designation Orbi- 

 culina adunca, which seems to have been conferred upon it by M. DESLONGSCHAMPS||. 

 79. A considerable number of figures of this species are given by M. D'ORBIGNY 

 in his treatise on the Foraminifera of Cuba, which forms part of the great work of 

 M. RAMON DE LA SAGRA on the Natural History, &c. of that island^. These figures, 



* Testacea Microscopica, Vindob. 1798. f Systeme des Animaux sans Vertebres. Paris, 1801. 



J Conchyliologie Systematique. Paris, 1808. 



Tableau Methodique de la Classe des Cephalopodes. Paris, 1825. 

 || Encyclopedic Methodique, Zoophytes. Paris, 1824. 

 ^f Histoire Physique, Politique, et Naturelle de 1'Ile de Cuba. Paris, 1840. 

 MDCCCLVI. 4 C 



