64 BRITISH FRESHWATER RHIZOPODA. 



Genus 2. DACTYLOSPHJERIUM Hertwig & 

 Lesser, 1874. 



Amoeba (pars) EHRENBERG in Abh. K. Akad. Wiss. Berlin, 

 1830 (1832), p. 39, and Infus. (1838), p. 128. 



Dactylosphserium HERTWIG & LESSER in Arch. f. Mikr. 

 Aiiat. X (1874), Suppl., p. 54. 



Body amoeboid; distinguished from Amoeba by the 

 possession, during the quiescent phase, of rigid or but 

 slightly flexuose pseudopodia, which radiate irregularly 

 from the sub-globular body-mass, and are variable in 

 number and length. Pseudopodal movements slow, 

 the pseudopodia often immobile for long periods ; 

 endoplasm as in Amoeba, generally colourless or only 

 slightly tinged with green, except in D. poly-podium. 

 The latter, in the density and colour of its endoplasm, 

 approaches Mastic/amoeba. 



The rigid and frequently elongated and pointed 

 pseudopodia (in the resting-phase) mainly characterize 

 this genus. D. radiosum is truly amoeboid in the 

 active phase. 



1. Dactylosphaerium radiosum (Ehrenb.) Biitschli. 

 (Plate III, figs. 8-11; PI. IV, figs. 6-11.) 



Amoeba radiosa EHRENBERG in Abh. K. Akad. Wiss. Berlin, 

 1830 (1832), p. 39; op. cit. 1831 (1832), p. 80; and Infus. 

 (1838), p. 128, t. viii, f. xiii; PRITCHARD, Nat. Hist. Ani- 

 inalc, (1834), p. 38 ; Hist. Infus. (1842), p. 166, t. ii, f. 88 ; 

 new ed. (1852), p. 202, t. ii, f. 88 ; and ed. 4 (1861), p. 549, 

 t. xxii, ff. 1-3; PERTY Kenntn. kleinst. Lebensf. (1852), 

 p. 188; COLE in Proc. EssexInst.I (1853), p. 45; SCHMARDA 

 G-rundz. Zool. I (1853), p. 26, f. 15; AUERBACH in Zeits. 

 f. wiss. Zool. VII (1856), p. 400, t. xxi; PICK in Verh. 

 Vereins Wien, VII (1857), p. 36; CARPENTER Foram. (1862, 

 Ray Soc.), p. 24, t. i, f. 15; t. iv, ff . 6, 7 ; CARUS Handb. 

 Zool. II (1863), p. 591 ; WALLICH in Ann. Nat, Hist. (3) 

 XI (1863), p. 443; WILLIAMSON in Pop. Sci. Eev. V 

 (1866), p. 197, t. xiii, ff. 14-16; CZERNY in Arch. f. 



