EXPLANATIONS AND REFERENCES, 



PLATE CLVIT. 



Figures magnified 500 diameters. 



PAGE. 



FigS. 1, 6. SCTADIUM ARBUSCULA, . . . . . .174 



" 1, 2. Young cells, ....... 174 



Fig. 3. Commencement of the first generation of daughter cells, . 174 



" 4. Farther progress of growth, . . . .174 



Figs. 5, 6. A second and a third generation, . . . .174 



" 7, 8. SCTADIUM GRACILIPES from a specimen from a pool, Minnesota, 175 



Fig. 9-11. STAUROGENTA CRUCIATUM, three different forms, . . 171 



'' 12. DICTYOSPHAERIUM HiTCHCOCKii, frequent in ponds, New 



Jersey, . . .186 



