126 BRITISH FRESHWATER RHIZOPODA. 



p. 56; and Freshw. Rhiz. N. Amer. (1879), p. 177, t. xxx, 



ff. 10-19 ; MAGGI in Atti Soc. Ital. XXI (1878), pp. 314, 



315; PARONA in Boll. Scient. I, an. 2 (1880), pp. 47, 48; 



and op. cit. II, an. 6 (1884), p. 56; HITCHCOCK Synops. 



Freshw. Rhiz. (1881), p. 27; TARANEK in Sitz.-ber. K. 



Bohm. Ges. Wiss. 1881 (1882), p. 225; GRIFFITHS and 



HENFREY Micr. Diet. ed. 4 (1883), p. 70, t. xxx, L 14 c ; 



McMuRRiCH in Proc. Canad. List. n.s. I (1883), p. 302 ; 



BLOCHMANN Mikr. Thierw. Siisswass. (1886), p. 12 ; and 



ed. 2 (1895), p. 15 ; WHITELEGGE in Proc. Linn. Soc. 



N. S. Wales, (2) I (1886), p. 501 ; PERRY in Proc. Amer. 



Soc. Micr. XII (1891), p. 95. 

 Arcella stellaris PERTY Mitth. naturf. Ges. Bern, 1849, 



p. 126; PENARD Faune Rhiz. Leman (1902), p. 410, ff. 

 Arcella OJceni PERTY Kenntn. kleinst. Lebensf. (1852), 



s. 186, t. ix, f . 4; PRITCHARD Hist. Infus. ed. 4 (1861), 



t. xxi, f. 15; MAGGI in Atti Soc. Ital. XXI (1878), 



pp. 314, 315. 

 Arcellina dentata CARTER in Ann. Nat. Hist. (2) XVIII 



(1856), p. 224. 

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



1871 (1872), p. 261, t, iii, f. 10. 

 Arcella Okeni var. BUCK in Zeits. f. wiss. Zool. XXX (1878), 



p. 4, t. i, 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. vidgaris. 



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 Leman,' 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. 



