90 FORAMINIFERA OF THE CRAG. 



pointed out that the chambers, whatever their convolutions, always retain a 

 paralleHsm with the polar axis of the test; also "that all the characteristic 

 features of these genera frequently occur in one and the same species;" nor did 

 he consider a definite number of segments to be an essential feature in this 

 consolidated genus (Miliolina). 



In 1860, " Miliola " was used by Parker and Jones as a comprehensive generic 

 term (' Ann. Mag. Nat. Hist.,' ser. 3, vol. v, p. 469) ; but, as Dr. H. B. Brady has 

 explained ('Challenger' Report, 188-i, pp. 137, 156, &c.), it is advisable to retain 

 Biloculina, Fabularia, and Spirolocnltna as separate genera, and to keep Triloculina, 

 Quinqueloculina, and Adelosina grouped together under the name Miliolina given 

 by Williamson. These four genera constitute the sub-family Miliolininae ; the 

 other sub-families — Nubecularinse, Rauerininse, Peneroplidinse, Alveolininas, and 

 KeramospJiserinse — completing the family Miliolidse. 



MM. Munier-Chalmas and C. Schlumberger, in their researches on the existence 

 of two conditions of growth in many species of Foraminifera, as first indicated for 

 Nummulites by Parker and Jones (' Ann. Mag. Nat. Hist.,' ser. 3, vol. viii, 1861, 

 p. 233, and ' Catal, Foss. Foram. Brit. Mus.,' 1882, p. 93), also for Orbitoides 

 (' Geol. Mag.,' vol. i, 1864, p. 103) ; and more fully studied by Ph. De la Harpe (see 

 letter dated October 1st, 1879, ' Catal. Foss. Foram. Brit. Mus.,' 1882, pp. 91—93, 

 and ' Mem. Soc. Pal. Suisse,' vol. vii, 1880-8, p. 63, &c.), discovered that such 

 "twin forms," "couples," or "dimorphs" occur in other genera besides 

 Nummulites.^ These forms were classed in two groups ; the one (A) with a large 

 initial chamber {megaloaphere), and the other (B) with a small initial chamber 

 {inicrofipliere). 



Among the '' Miliolidx" they separated and defined, by means of carefully 

 prepared internal sections, showing the relative size of the primordial chamber, 

 and the arrangement and character of the segments of the test, the following 

 forms : — Biloculina, Dillina, Fabularia, Lacazlna, Triloculina, Trillina, Quinque- 

 loculina, Pentellina, and Heterillina. Subsequently^ Idalina, Adelosina, Perilocu- 

 lina, Massilina, Spiroloculina, and Sigmoilina ; besides others, as Nodosaria, 

 Dentalina, Gristellaria, Siphogenerina, Orbulina, Botalina, and Amphistegina (see 

 E. Vanden Broeck, ' Bull. Soc. Beige Geol. Paleont. Hydrolog.,' vol. vii, 1893, 

 pp. 6—41). 



In 1884, H. B. Brady (in the ' Challenger ' Report, pp. viii and ix) gave a 



1 ' Bull. Soc. Geol. France,' ser. 3, vol. viii, 18S0, p. 300 ; ' Comptes Eendus,' vol. xcvi, 1888, 

 pp. 862—866, and pp. 1598—1601 ; ' Anu. and Mag. Nat. Hist.,' ser. 3, vol. xi, 1883, pp. 340, 341. 



2 'Assoc. Fran?. Congros Eochelle,' 1883, pp. 230—232; ' Congres Eouen,' 1884, pp. 520—527; 

 ' Bull. Soc. Geol. France,' ser. 3, vol. xii, 1884, pp. 629, 630; vol. xiii, 1885, pp. 273—323; vol. xv, 

 1887, pp. 573—584 ; ' Bull. Soc. Zool. France,' vol. xi, 1886, pp. 544—557 ; ' Mem. Soc. Zool. France,* 

 vol. iv, 1891, pp. 542—578; vol. vi, 1893, pp. 57-80. 



