18 FORAMINIFERA OF THE CRAG. 
arbuscula is one of the most interesting in a zoological point of view; and the careful 
study of its peculiarities has been one of the chief means of reducing to a proper level the 
exaggerated views held by M. D’Orbigny and others as to the value of the form and 
character of the pseudopodial apertures in the determination of species amongst the 
Rhizopods. Dr. Carpenter has entered very fully into this question (‘ Phil. Trans.,’ 1859 ; 
and ‘ Introduction,’ pp. 88—91), and all who have had the opportunity of examining large 
numbers of specimens will agree in his conclusions. 
Dendritina Antillarum, D’Orb., 1839, ‘ Foram. Cuba,’ 'D. 58, pl. 7, figs. 3—6; and 
D. Hauerii, D. Juleana, and D. elegans, D’Orb., ‘ For. Foss. Vien.,’ p. 134, pl. 7, figs. 
1—6, are but slightly modified forms, or rather variously conditioned individuals, of the 
nautiloid Peneroplis under consideration. 
Dendritina arbuscula has not so wide a distribution as the other varieties of Peneroplis, 
and the specimens are generally smaller than those of the outspread varieties. It has its 
home in shallow seas in tropical latitudes; and it is abundant in some parts of the Adriatic 
and Mediterranean. In the Tertiary beds it is occasionally met with as low as the 
Miocene of Bordeaux, the Oligocene of Germany, and even the Eocene of the Paris Basin. 
The specimen figured by us from the Crag is, we believe, unique, and has a somewhat 
worn appearance. It is either from Sudbourne or Gedgrave. 
Subgenus—SPIROLINA CYLINDRACEA, Lamarck. 
SPIROLINA (SPIROLINITES) CYLINDRACEA, Lamarck, 1804. Ann. Mus., vol. v, p. 245, No. 2 
1806, ibid., vol. viii, p. 388, pl. 62, fig. 15; 
1816, Tabl. Enc. Méth., part 23, pl. 465, fig. 
7 a-c, and pl. 466. fig. 2, a,b; 1822, Hist. 
Anim. s. Vert., vol. vii, p. 603, No. 2. 
SPIRULA CYLINDRACEA, Blainville, 1824. Dict. Sc. N., vol. xxxii, p. 190; Malacol., p. 382, 
pl. 5, fig. 1. 
SPIROLINA CYLINDRACEA, D’ Orb., 1826. Modéle, No. 24; Ann. Sc. Nat., vol. vii, p. 286, No. 1. 
— (et SPIROLINITES) CYLINDRACEA, Defr., 1827. Dict. Sc. Nat., vol. 1, p. 298, 
pl. 13, fig. 1. 
— CLAVATA, Crouch, 1827. Illust. Introd. Lam. Conch, p. 40, pl. 20, fig. 8. 
—_ CYLINDRACEA, Bronn, 1838. Leth. Geog., vol. ii, p. 1135, pl. 42, fig. 24. 
et PENEROPLIS, var., Carpenter, 1859. Phil. Tr., vol. cxlix, pl. 2, fig. 11; 1862, 
Introd., p. 88, pl. 7, fig. 4. 
PENEROPLIS PLANATUS (F. and M.), var., Parker and Jones, 1859. Ann. Nat. Hist., ser. 3, 
vol. iii, p. 481; 1860, ibid., vol. v, p. 466. 
— pertusus (Forsk.),! var., Parker, Jones, and Brady, 1865. Ibid., vol. xv, 
pp. 231, 232. 
SPrROLINA CYLINDRACEA (Lam), P. J. and B., 1865. Ibid., vol. xvi, p. 22. 
1 The wide variation in eharacter presented specimens referable to the Peneroplid type has caused 
