THE LOBOSA 



digitiform pseudopodia. In this species there may be either one or 

 many nuclei. It may reach a size of 200 /A in diameter. A. guttula 

 (Fig. 12, 4) is another very common species of small size, 30 /A, which 

 shows slow undulating movements of the ectoplasm but rarely 

 protrudes definite pseudopodia. In Amoeba Umax (Fig. 12, 2), which 

 is slug-like in form, the end that is posterior in progression shows 

 a fan -shaped arrangement of short ridges, due probably to the 



FIG. 12. 



Different species of freshwater Gymnamoebida. 1, Dactylosphaera radiosa, x 260. 2, 

 Amoeba Umax, x 200. 3, Amoeba verrucosa, x 200. 4, Amoeba guttula, Duj., regarded as a young 

 form of A. proteus by Leidy. 5, Amoeba proteus. 6, Amoeba (Ouramoeba) vorax, x 130. N, 

 nucleus ; c.v, contractile vacuole ; F.v, food vacuole ; F, hyphae of a fungus. In Amoeba vorax 

 some of the large diatoms (D, D) upon which it feeds and the approximate positions of the 

 nucleus and contractile vacuole are shown. (1, 2, 3 from Cash ; 4, 5, 6 from Leidy.) 



wrinkling of the surface in the vortex of the retreating axial stream 

 .{see p. 69). 



The marine Amoebae have not yet been carefully recorded. 

 Amoeba crystalligera is often found in marine aquaria, and a species 

 allied to the freshwater A. guttula has been found at Woods Hole 

 in America. Amoeba fluida was found in sea- water aquaria in 

 Freiburg by Gruber, and this with two other species were also 

 found by him in the Gulf of Genoa. 



