ARCELEA MITRATA. 125 
prominent folds; base rounded at the border, inverted, 
concavely infundibuliform, mouth circular, crenu- 
lated, mostly everted within the inverted funnel. 
Plasma-body spheroidal, usually connected with the 
mouth by a cylindrical neck, and attached by threads 
of endoplasm to the interior of the test. Pseudopods 
variable in number, up to half a dozen or more. 
Dimensions: Height of test 100-145; diameter 
100-152 yp (West). 
Amongst Sphagnum and Utricularia minor, Cocket 
Moss, Giggleswick, West Yorkshire; and in Sphagnwm- 
pools on Moel Siabod, North Wales (G. S. West). 
Professor Leidy (whose description we quote) found 
this species abundant in some parts of Pennsylvania, 
but in Europe it seems very scarce. West (loc. cit.) 
remarks: “The mouth of the shell of this rhizopod is 
inturned into the cavity of the shell, forming a short, 
broad, tube-like mouth. Leidy figures the pseudo- 
podia as arising from the body-protoplasm at the 
inner end of the tube; but in all the living forms 
observed, a ventral column of protoplasm passed from 
the body-protoplasm into this tube, completely filling 
it to the outer end. The pseudopodia then arose from 
the extreme ventral surface of this mass of protoplasm 
in the tube.” 
4. Arcella dentata Ehrenberg. 
(Plate XV, figs. 7 and 8; and figs. 21-23 im text.) 
Arcella dentata Exrenserc in Abth. K. Akad. Wiss. Berlin, 
1830 (1832), pp. 31, 40, 71; op. cit. 1831 (1832), p. 90; 
Infus. (1838), p. 134, t. ix, f. vil; and in Ber. K. Akad. 
Wiss. Berlin, 1853, p. 255; Prircuarp Hist. Infus. (1842), 
p. 170; new ed. (1852), p. 211; and ed. 4 (1861), p. 155; 
Rymer Jones in Todd’s Cycl. Anat. IV (1847), p. 10, £. 7, 
no. 2; Bartey in Smithson. Contrib. II (1851), art. 8, 
passim; Perry in Mitth. naturf. Ges. Bern. 1849, p. 163, 
and Kenntn. kleinst. Lebensf. (1852), p. 186; Luzpy in 
Proc. Acad. Nat. Sci. Phil. 1874, p. 14; op. cit. 1876, 
