70 BRITISH. FRESHWATER RHIZOPODA. 
narrowed anteriorly, and forming a conical lobe or 
prominence from which emanates a long and active 
flagellum. Pseudopodia short, radiating {qutwards 
from the cortical ectoplasm, simple or ramulose. The 
body-surface, in at least one species, is habitually 
covered with minute bacilliform spiculee. 
1. Mastigameba aspera IF. E. Schulze. 
(Plate VI, figs. 1-5.) 
Mastigameba aspera F. K. Scuutze in Archiv. f. mikr. Anat. 
XI (1875), p. 583, t. xxxv; ALLMAN in Journ. Linn. Soc., 
Zool. XIII (1877), p. 268, f. 8; Arcugpr in Q. J. Micr. 
Sci. XVII, ns. (1877), p. 350, t. xxi, f. 24; Kuwr Man. 
Infus. I, pt. 2 (1880), p. 221, t. i, f. 21; Lanzssan Traité 
Zool., Prot. (1882), p. 50, f. 88; Birscurr in Bronn’s 
Thier-Reichs, I, 2 (1888), t. xxxix, f. 9; Grirriras & 
Henrrey Micr. Dict. ed. 4 (1883), p. 492, t. liii, f. 22; 
Hertrwie Lehrb. Zool. I (1891), p. 147, f. 43; ed. 2 
(1900), p. 159, f. 118; and (Engl. transl.) Man. Zool. 
(1908), p. 188, f. 118; Catxins Prot. (1901), p. 103, 
f. 57a, 
Animal, in the resting phase, sub-spherical or oval, 
ultimately, when in active movement, becoming elon- 
gated and narrowed anteriorly, whilst the posterior ex- 
tremity remains rounded, or, in what may be younger 
individuals, is produced into arounded lobe. The body 
is susceptible of considerable modifications, changing 
from globular to oval, or becoming bluntly angular, 
whilst throwing out numerous amoeboid pseudopodia, 
in which condition the organism is hardly distinguish- 
able from some forms of Amba, except by its highly- 
refringent and denser protoplasm. In the mobile 
state (Pl. VI, fig. 1) the pseudopodia are numerous, 
variable in length, usually simple and straight, rarely 
bigeminate or forked, mostly attenuated but blunt at 
the apex, and never becoming filamentous or acicular. 
The posterior ones are short; those immediately in 
front, on either side of the frartal lobe, longer and 
