20 Infusoria from Fresh Water. [ January, 
the Ehrenbergian species, and has not the densely granu- 
lated parenchyma of the latter. In color it is a translucent 
homogeneous emerald-green. It has a frequently exercised 
tendency to a characteristic change of form by retracting the 
borders of one side of the extended body so as to produce a 
deep depression, while the contracted zodid exhibits a habit 
of some slight diagnostic value in the sheathing of the dis- 
tal end of the pedicel by the posterior extremity of the body. 
The cuticular surface is transversely striated by depressions so 
fine that they are ordinarily visible only at the lateral borders or 
after manipulation of the mirror. Minute granules occasionally 
Fig. 3. Fig. 4. Fig. 5. 
Fic. 3.— Vorticella smaragdina, sp. nov., showing lateral depression. X 180. FIG- 
4.—Diagrammatic outline of V. smaragdina when extended. Fic. 5.— Vorticella 
macrocaulis, sp. NOV. X 360. 
roughen the surface and are barely visible under an amplification 
of 250 diameters, when they appear to add to the distinctness of 
the transverse striations without making themselves conspicuous, 
With magnification of 400 diameters they are seen to be minute, 
dark-bordered refractive particles arranged in no apparent order 
and having no connection with the surface strie. They are not 
constantly present, and their absence seems to add to the beauty 
of this peculiarly attractive creature. When the infusorian is well 
and the surroundings are auspicious, but little of the contracted 
pedicel remains uncoiled, this atomie of living emerald then 
quivering at the summit of a crystalline spring, like a spherule of 
ch rase on a coil of silver thread, 
