180 Transactions of the [^^^j; T.'nTiX"' 



II. — On the Shell-structure of Fusulina. 

 By W. B. Carpenter, M.D., F.E.S. 



(Bead be/ore the Eoyal Microscopical Society, March 9, 1870.) 

 Plate XLV. 

 The Genus Fusulina was instituted in 1829 by Fischer de Wald- 

 heim for the reception of a group of fusiform Foraminifera, often 

 attaining a considerable size, which occur in such abundance in 

 certain beds of the AVhite Carboniferous Limestone of Eussia as to 

 constitute the principal part of their material ; entire specimens, as 

 in the comparatively modern Nummulitic or Alveolina Limestone, 

 being imbedded in a matrix which is in great part composed of 

 fragments of the same organisms intermingled with other Microzoa. 

 In consequence of its very close resemblance to Alveolina, both in 

 external form and in general plan of structure, it has been ranked 

 by many systematists in close proximity to that genus ; and this 

 position was assigned to it even by my excellent fellow-labourers 

 Messrs. Parker and Eupert Jones,* notwithstanding that they 

 remarked the essential difference between the single nummuline 

 aperture which D'Orbigny had long before shown to be character- 

 istic of Fusulina, and the multiplied pores which are distributed 

 over the whole septal plane of Alveolina. IMy own investigations 

 led me to the conclusion that the relation of Fusulina to Alveolina 

 is one of isomorphism only, corresponding to that which frequently 

 presents itself between types respectively belonging to the porcel- 

 lanous or Imperforate and to the vitreous or Perforated series. 

 For not only did they confirm the view of D'Orbigny as to the 

 essential conformity of Fusulina, as regards its general structure, to 

 the Nummuline type, but also afforded what I regarded as distinct 

 evidence of perforation of the chamber-walls by closely-set joarallel 

 tubuli, intermediate in diameter between the fine tubuli character- 

 istic of Nummuline shells and the coarse pores usually seen in the 

 Eotaline. That the indications of the tubuli are not more dis- 

 tinct, and that no determination can be made of their precise 

 diameters, arises from the metamorphic condition in which these 

 shells are usually found ; their ultimate texture having been greatly 

 altered by molecular change, as is the case with most of the fossils 

 imbedded in the Carboniferous Limestone.! 



It was with great satisfaction that I subsequently found that 

 Professor Eeuss, having been led to adopt the ultimate texture of 

 the shell as the basis of his classification of Foraminifera, had 

 unhesitatingly ranked Fusulina in his series of vitreous finely-tubular 

 shells, placing it after Nonionina in his family Polystomellidea, so 

 as to lead to his family Nummulitidea.X 



* ' Ou the Nomenclature of the Foraminifera,' Part VI., ' Anna, of Nat. Hist.,' 

 3rcl ser., vol. viii. (1861), p. 161. 



t See my 'Introduction to the Study of the Foraminifera,' pp. 304-7. 



X ' Entwurf einer Systematischen Zusammen stellung der Foramiuiferen,' in 

 ' Sitzungsberichte der mathematisch-naturwissenf3chaftlichen. Classe dea kaip. 

 Akad. der Wisseiichafton,' Bd. xliv. Wien, 1861. 



