18 FORAMINIFERA OF THE CRAG. 



arhuscula is one of the most interesting in a zoological point of view ; and the careful 

 study of its pecidiarities 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. 



Dendrifina Antillarum, D'Orb., 1839, 'Foram. Cuba,' p. 58, pi. 7, figs. 3 — 6; and 

 D. Hauerii, D. Juleana, and B. elegans, D'Orb., 'For. Foss. Vien.,' p. 134, pi. 7, figs. 

 1 — 6, are but slightly modified forms, or rather vai'iously 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 OHgocene of Germany, and even the Eocene of the Paris Basin. 



The specimen figured by us from the Crag is, we believe, luiique, and has a somewhat 

 worn appearance. It is either from Sudbom-ne or Gedgrave. 



Subgenus — Spirolina cylindracea, Lamarck. 



Spikolina (Spikolinites) cylindkacea, Lamarck, 1804. Ann. Mus., vol. v, p. 245, No. 2 ; 



1806, ibid., vol. viii, p. 388, pi. 62, fig. 15; 



1816, Tabl. Enc. Metli., part 23, pi. 465, fig. 



7 a-c, and pi. 466. fig. 2, a, b ; 1822, Hist. 



Anim. s. Vert., vol. vii, p. 603, No. 2. 

 Spieula cylindracea, Blainville, 1824. Diet. So. N., vol. x.\xii, p. 190 ; Malacol., p. 382, 



pi. 5, fig. 1. 

 Spirolina cylindracea, D'OrS., 1826. Module, No. 24 ; Ann. So. Nat., vol. vii, p. 286, No. 1. 



— (et Spirolinites) cylindracea, Befr., 1827. Diet. Sc. Nat., vol. 1, p. 298, 



pi. 13, fig. 1. 



— clavata. Crouch, 1827. lUust. Introd. Lam. Conch, p. 40, pi. 20, fig. 8. 



— cylindracea, iJroran, 1838. Leth. Geog., vol. ii, p. 1135, pi. 42, fig. 24. 



— et peneroplis, var., Car/)em^er, 1859. Phil. Tr., vol. cxlix, pi. 2, fig. 1 1 ; 1862, 



Introd., p. 88, pi. 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. 

 Spirolina cylindracea (Lam), P. J. and B., 1865. Ibid., vol. xvi, p. 22. 



^ The wide variation in character presented specimens referable to the Peiieroplid type has caused 



