Nomenclature of the Foraminifera. 109 



Nummulina, like other Foraminifera, take such licence in their 

 mode of growth, in the relative size and setting-on of the segments 

 and their alar lobes, and in the exaggeration of the exposed 

 septal lines and pillars by the, as it were, capricious growth of 

 shell-matter, that it is difficult, even with the best- grown of 

 these giants of the family, to determine where anything like 

 specific limits can be marked out. 



It appears to us that, in its style of growth, Nummulina is 

 related to Operctdina, so closely, indeed, that, like Assilina, 

 the latter sinks to the low grade of a subvarietal condition, there 

 being no strict boundary between it and Nummulina, as we find 

 abundantly proved by both recent and fossil specimens. Just 

 so Nonionina loses itself in Polystomella. 



The hundreds of indifferently described Nummulitic forms to 

 be found in geological works were in 1853 reduced to order by 

 the combined labours of M. le Vicomte d'Archiac and M. Jules 

 Haime, and arranged as fifty-two species, grouped in six sections, 

 namely, 1. Nummulinse Iseves aut sublseves; 2. Reticulate; 

 3. Subreticulatse ; 4. Punctulatse; 5. Plicate vel striatse ; 6. Ex- 

 planatse (septa et spira plus minusve prominentes), Nos. 15 

 forming the division characterized by "cloisons embrassantes, 

 plus ou moins inclinees et arquees," No. 6 being a division by 

 itself, with " cloisons non embrassantes et presque droites." 



The group No. 1 , " Iseves," have the alar or umbilical lobes 

 attenuate (corresponding to the smallness of the segments) and 

 extremely sinuous, "filets cloisonaires simples, tres-sinueux." 

 This is the chief characteristic of the large, flat, smooth Num- 

 mulites forming the group, of which N. complanata, Lamarck, 

 is the type. We should have preferred the term " sinuatse " 

 or " complanatse" for the group. Groups No. 2 and No. 3, 

 " reticulate " and *' subreticulatse," are characterized by the 

 inosculation of the "filets cloisonaires" or alar lobes of sarcode 

 proceeding laterally from the segments; they are so closely 

 related, that we may regard them as one group, characterized by 

 the net-like arrangement of the inosculating lobes, "reseau 

 cloisonaire," and typified by N. lavigata, Lam. The "punc- 

 tulatse " of group No. 4 are, we believe, artificially brought to- 

 gether : they belong part to group 1 and part to group 5, and 

 in some cases have very close relations with groups 2 and 3. 

 The feature referred to as characteristic in group No. 4 is the 

 granulation of the surface ; and, owing apparently to the strange 

 mistake of the authors (formerly made also by Dr. Carpenter in 

 his Memoir on Nummulites in the Quart. Journ. Geol. Soc. 

 vol. vi.*) in regarding the subcrystalline columns seen in sections 

 of Nummulites (that is, the septal walls and pillars) as calcareous 



* Corrected by him in Phil. Trans, vol. exlvi. p. 558, note. 



