126 BRITISH FRESHWATER RHIZOPODA. 
p. 56; and Freshw. Rhiz. N. Amer. (1879), p. 177, t. xxx, 
ff. 10-19; Magar in Atti Soc. Ital. XXI (1878), pp. 314, 
315; Parowa in Boll. Scient. I, an. 2 (1880), pp. 47, 48; 
and op. cit. II, an. 6 (1884), p. 56; Hircucock Synops. 
Freshw. Rhiz. (1881), p. 27; TarAnex in Sitz.-ber. K. 
Béhm. Ges. Wiss. 1881 (1882), p. 225; Grirriras and 
Hewrrey Micr. Dict. ed. 4 (1883), p. 70, t. xxx, f. 14c; 
McMourricy in Proc. Canad. Inst. n.s. I (1883), p. 302 ; 
Brocumann Mikr. Thierw. Siisswass. (1886), p. 12; and 
ed. 2 (1895), p. 15; Wauiretnaer in Proc. Linn. Soe. 
N.S. Wales, (2) I (1886), p. 501; Perry in Proc. Amer. 
Soc. Micr. XII (1891), p. 95. 
Arcella stellaris Party Mitth. naturf. Ges. Bern, 1849, 
p. 126; Pewarp Faune Rhiz. Léman (1902), p. 410, ff. 
Arcella Okent Perry Kenntn. kleinst. Lebensf. (1852), 
s. 186, t. ix, f. 4; Prircnarp Hist. Infus. ed. 4 (1861), 
t. xxi, f. 15; Macear in Atti Soc. Ital. XXI (1878), 
pp. 314, 815. 
Arcellina dentata Carter in Ann. Nat. Hist. (2) XVIII 
(1856), p. 224. 
Arcella stellata Hurensera in Abh. K. Akad. Wiss. Berlin, 
1871 (1872), p. 261, t. iii, f. 10. 
Arcella Okent var. Bucx in Zeits. f. wiss. Zool. XXX (1878), 
p. 4, t. 1, ff. a, D 
Test, in ventral and dorsal aspect, circular, and 
more or less dentated ; in lateral view crown-like, the 
breadth more than twice the height; dome convex 
and even, or depressed at the summit and broadly 
fluted at the sides, the base centrally inverted, con- 
cavely infundibuliform; at the periphery more or less 
everted and divided into points of variable length. 
The mouth circular, entire. Protoplasm resembling 
that of A. vulgaris. 
It is doubtful if typical A. dentata has been found 
in Britain, but we have met with a peculiar form much 
resembling Penard’s figure (‘Faune Rhiz. du Bass. 
du Léman,’ p. 411), but differing from it in the 
shallower non-punctated test, and less robust spines. 
When viewed dorsally the spines radiated from the 
periphery of the membranous test; viewed laterally 
they were divergent, pointing upwards from the base. 
