A.ND OTHER ENGLISH NTJMMTJLITES 



141 



Among Nummulites in general, the same pairing of species holds 

 good, thus : — 



Central chamber 



Small. 

 N. perforates. 

 N. Brongniarti. 

 N. complanatus. 

 N. gizensis. 

 N. contortus. 

 N. biaritzensis. 

 Assilina exponens. 

 A. spira. 



Large. 



N. Lucasanus. 

 K. Molli. 

 N. Tchihatcheffi. 

 N. currispira. 

 N. striatus. 

 N. Guettardi. 

 Assilina mamillata. 

 A. subspira. 



See Catal. Foss. Eoram. Brit. Mus. pp. 92, 93. 



The constant association, in the same strata, of large individuals 

 with a small, and small individuals with a large central chamber, is 

 more fully treated in Dr. Ph. De la Harpe's " Memoir on the 

 Nummulites of Switzerland" (Mem. Soc. Pal. Suisse, vol. vii. 1881), 

 at p. 63, &c, thus carrying out to a practical result the obser- 

 vations made by Prof. Parker and myself in the ' Annals Nat. Hist.' 

 ser. 3, vol. vii. 1861, p. 233. Dr. De la Harpe, however, appears 

 not to have seen this paper, nor our " Notes on Nummulites," 

 op. cit. vol. v. 1860, pp. 109, 294, &c. ; nor Carpenter, Parker, 

 and Jones's observations in the ' Introd. Study Eoram.' Ray Soc. 

 1862, pp. 262-276 ; at least he does not refer to them in detail. 



1881. " Etude des Nummulites de la Suisse," &c, premiere 

 partie, Mem. Soc. Paleontol. Suisse, vol. vii. At page 29, referring 

 to some forms which he thought that D'Archiac had confused under 

 the name of planulata, Dr. De la Harpe stated that the little form, 

 with large central chamber, figured by Sowerby as N. elegans, ' Min. 

 Conch.' pi. 538. figs. 6-11 [Sowerby's " fig. 2 "], and taken by 

 D'Archiac for young N. planulatus, should retain the name given by 

 Sowerby. 



I consider the nos. 6-9 and 11 (in " fig. 2 ") to be really 

 N. planulatus of different stages of growth ; but, coming under that 

 genus instituted by Lamarck, they did not require a new name ; 

 whilst " no. 10 " is one of the specimens on Sowerby's card labelled 

 " Nwmmularia elegans" and forming the chief subject of his para- 

 graph on N. elegans, op. cit. p. 76. 



Dr. De la Harpe having found some small lenticular planulati 

 with a large central chamber, regards them as one of his twin 

 species. Nos. 7 and 8 in Sowerby's " fig. 2 " are like these exter- 

 nally, and may or may not have the large central chamber. At 

 all events they either are or have been mixed up, in the siliceous 

 rock of "Emsworth," with planulatus (nos. 6-9, and 11). Even 

 if they be the same as De la Harpe's twin species referred to 

 (Numm. Suisse, pi. 7. figs. 12-23), they cannot be called elegans, as 

 that name is on Sowerby's label of the Prestwichiana variety from 

 Alum Pay. 



