102 FORAMINIFERA OF THE CRAG. 



M. Sclilumberger does not admit Signor Fornasini's pi. v, fig. 1 (quoted 

 above), to be a true B. hulloides ('Bull. Soc. Geol. France,' 1887, p. 574), on 

 account of some difference of internal structure. In referring (loc. cit.) to the 

 confusion of the species {B. hulloides and B. ringens), he rightly blames the often 

 indifferent figures and imperfect descriptions given by former writers, as well as the 

 dearth of information about the internal structure. Another reason, however, for 

 this apparent confusion is that the classifications of Foraminifera have been based 

 on the existence of zoological type-forms (whether generic or specific), the other 

 forms having been grouped more or less closely with them. Thus BilocuUna ringens 

 was taken as one Milioline type, and M. seminulum as another by Parker and 

 Jones (1857, 1860, &c.), by Williamson (1858), by Goes (1882), by Brady (1884). 

 Consequently great latitude of opinion has arisen on the subject of the relation- 

 ship of these almost interminably gradational, and often isomorphous forms. Simi- 

 larly this holds good to a great extent among the members of the genus Nodosarina 

 proposed by Parker and Jones. The differentiation of internal structures, as 

 shown by MM. Munier-Chalmas and Schlumberger, and the researches carried on 

 now-a-days in the life-history of some of the Foraminifera,^ raise hopes of a better 

 distinction of forms, and of a more perfect classification. 



Occurrence. — The typical BilocuUna hulloides is recorded as common in the North 

 Atlantic, but more rarely in other latitudes ; and it has a wide bathymetrical range. 

 It is a common Tertiary fossil. The var. inornata has been found in the Miocene of 

 Vienna, the Tertiaries of Piedmont, and the Diestian and Scaldisian of Antwerp. 

 In the Crag we find it, small and very rare, at Sudbourne Hall, Gedgrave, and 

 Sutton. 



Genus 2. — Spieolocclina, d'Orhigny, 1826. 

 Part' I, 1866, page 15. 



D'Orbigny, ' Foram. Foss. Tert. Vienne,' 1846, p. 268; Brady, Report 

 'Challenger,' 1884, p. 147; Egger, ' Abhandl. k. Bayer. Akad.,' 1893, 

 vol. xxviii, Abth. 2, p. 221. 



General Characters. — Chambers opposite, alternate, in one plane ; all visible on 

 both sides (faces) of the shell. 



For convenience it is found best to arrange the more common Spiroloculinse 

 in six groups according to certain features which are recognisable in different 



^ See also J. J. Lister's " Contributions to the Life-liistory of the Foraminifera," ' Proc. Eoy. 

 Soc.,' vol. Ivi, No. 337, 1894, pp. 155—160. 



- In the last line but one of the synonyms at p. 15 read p. 470 instead of p. 466. 



