118 BRITISH FRESHWATER RHIZOPODA. 



and finally assume its character and habits. These are 

 not infrequently met with, fully developed, but distin- 

 guished from older individuals by their delicate texture 

 and transparency. 



1. Arcella vulgaris Ehrenberg. 



(Plate XV, figs. 1-3 and 13-15, and figs. 17 and 18 



in text.) 



Arcella vulgaris EHRENBERG in Abh. K. Akad. Wiss. Berlin, 

 1830 (1832), p. 40, t. i, f. vi ; op. cit. 1831 (1832), p. 90 ; 

 op. cit. 1871 (1872), p. 234 ; Infus. (1838), p. 133, t. ix, 

 f. v; in Ber. K. Akad. Wiss. Berlin, 1845, p. 307; op. cit., 

 1853, pp. 255,266; and in Mouatsb. K. Akad. Wiss. 

 Berlin, 1869, p. 260; BLAINVILLE Man. d'Actinol. (1834), 

 p. 623; DUJARDIN Infus. (1841), p. 247, t. ii, ff. 3-5; 

 PRJTCHARD Hist. Infus. (1842), p. 169; new ed. (1852), 

 p. 211 ; and ed. 4 (1861), p. 555, t. xxi, ff. 7-9; SCHMARDA 

 Kleiue Beitr. Naturges. Infus. (1846), p. 30 ; in Denks. 

 K. Akad. Wiss. Wien, VII (1854), 2, pp. 20, 25 ; and Zoo}. 

 (1871), p. 163, f. 55; SIEBOLD Anat. Wirb. Thiere (1848), 

 p. 20, and (Engl. transl.) Anat. Invert. (1854), p. 30 ; 

 PERTY in Mitth. naturf. Ges. Bern, 1849, pp. 124, 163, 

 and Kenntri. kleinst. Lebensf. (1852), p. 186, t. ix, ff. 1-3; 

 BAILEY in Smithson. Contrib. II (1851), art. 8, passim; 

 COLE in Proc. Essex Inst. I (1853), p. 45 ; CLAPAREDE in 

 Arch. 'f. Anat. 1854, pp. 401, 419; OWEN Anat. Invert. 

 Anim. ed. 2 (1855), p. 26; CARTER in Ann. Nat. Hist. (2) 

 XVIII (1856), pp. 128, 132, 221, t, vii, f. 79, and op. cit. 

 (3) XIII (1864), p. 30, t. ii, f. 14 ; LIEBERKUHN in Arch. 

 f. Anat. 1856, p. 33 ; CLAPAREDE & LACHMANN .Etudes 

 Inf. et Rhiz. 2 (1859), p. 444; G-OSSE Ev. Micr. (1859), 

 p. 462; CARPENTER Foram. (1862, May Soc.), t. i, f. 19; 

 CARUS Handb. Zool. II, Prot. (1863), p. 591; ARCHER in 

 Q. J. Micr. Sci. VI, n.s. (1866), pp. 185, 186, and in Q. J. 

 Micr. Sci. XVII, n.s. (1877), p. 79 ; SCHOCH Mikr. Thiere, 

 I (1868), p. 14, t. i, f. 21 ; ENGELMANN in Arch. f. ges. 

 Physiol. II (1869), p. 318, and in Arch. Neerl. IV (1869), 

 pp. 424, 438, t. vii, ff. 4, 5; PARFiTT^in Trans. Devon. 

 Assoc. Ill (1869), p. 67; HERTWIG & LESSER in Arch, 

 f. mikr. Anat. X (1874), Suppl. p. 96; LEIDY in Proc. 

 Acad. Nat. Sci. Phil. 1874, p. 14; op. eft. 1876, p. 55; 

 op. cit. 1879, p. 162; and Freshw. Rhiz. N. Amer. (1879), 

 p. 170, tt. xxvii, xxviii, ff. 1-7; BUTSCHLI in Arch. f. mikr. 

 Anat. XI (1875), p. 459, t. xxv, and in Bronn's Thier- 



