MASTIGAM@BA ASPBRA. “1 
narrower, and generally pellucid. The arrangement 
of the pseudopodia, in this aspect of the animal, is 
fairly regular: they extend outwards from the margins 
of the compressed body, being, in fact, extensions of 
the ectoplasm, and appear to occupy a common plane. 
The refringent character of the ectoplasm extends also 
to the pseudopodia, and is heightened by the presence 
of innumerable minute spicule which adhere to the 
surface tangentially or horizontally. The nucleus is 
single, imbedded in the anterior ectoplasm just behind 
the frontal lobe, and is sometimes hidden by the semi- 
Opaque granular endoplasm. From this lobe the 
flagellum extends outwards, its point reaching beyond 
the extremities of the pseudopods; it is hyaline, very 
refractive, and always alert, moving and coiling with 
great rapidity ; from which circumstance it is not in- 
frequently difficult of detection. Contractile vesicles, 
usually two, on opposite sides of the body, in the 
posterior region. 
Dimensions variable: length averaging 150-200 p; 
average breadth about 50 p. 
In the ooze of ponds, and amongst floating vegeta- 
tion, at Chelford and Northenden, Cheshire; and at 
Fearnhead, Lancashire. 
The facial aspect of Mastigamaeba aspera differs 
remarkably from that of the larger dinwbe with which 
it might be confounded. It attracts attention at once 
by its refringent protoplasm. The flagellum, its pecu- 
liarly-distinctive feature, is stated by F. E. Schulze to 
be 0:06-0:08 mm. long, and is rightly described by 
him as “a very fine filament of equable but hardly- 
defineable character, and considerable refractive power.” 
It is not attenuated at the extremity but of equal 
thickness throughout, and ends “as if abruptly cut off.” 
The movements of the animal are distinctly amceboid ; 
the action of the flagellum has no effect as an organ of 
locomotion, though in very young and small indi- 
viduals its rapid movements do seem at times to 
