130 DKSCRTPTTON OF [Poli/ffasfrtca. 



ample, see Table, p. 117.) The Glenomonim closely resembles the 

 Vvella, but differs from that genus by the superaddition of the red 

 eye ; it differs from Monm and lEcrocjlena in occasionally aggregating 

 from Chilomonas, in being deficient of the projecting lips ; from Bodo, 

 in not having the tail ; fi'om Phacelomonas, by the double proboscis ; 

 from BoxococcuH, by swimming, instead of rolling over or revolving 

 in the water ; and from Polytoma, by never appearing in clusters 

 whilst undergoing self-division. 



Glenemoetjm tingens. — Body fusiform, of a beautiful gi'een colour, 

 and three or four times longer than it is broad. Its double proboscis is 

 exceedingly delicate, and about half the length of its body; within it 

 may be seen some small whitish vesicles, the stomach-cells, and also 

 some minute granules, which give rise to the green colour, and may be 

 considered ova. About the centre of the body is a large transparent 

 colourless organ, which Ehrenbcrg supposes to be of a male sexual 

 nature. The beautiful red eye is fijs^ed internally, about one-thu'd 

 from the anterior extremity of the body. These animalcules con- 

 stitute a great portion of the green matter commonly seen on stagnant 

 water, and discovered by Priestley. They appear to be nearly allied 

 to Cercaria viridis, differing from this only in magnitude, and in the 

 unalterable form of their bodies. Figure 15 represents two clusters ; 

 16, single ones, magnified 250 times; 17, another magnified about 

 450 diameters. Found plentiful at Hampstead. Size 1 -3600th to 

 1-1 700th. 



Genus Doxococctrs. Tlie revolving Monads. — The individuals of this 

 genus differ from those of the whole family Monadina by the singularity 

 of theii- motion, which may be defined to be neither that of swim- 

 ming nor of rotation, but a sort of rolling over and over. In other 

 particulars they are like the Monads. They have the same imvary- 

 ing form, and are destitute of the eye, projecting lips, and tail. Their 

 self-division is simple and complete, or they do not divide at all, in 

 which ease they increase by ova. These character are sufficient to 

 distinguish them from all other Infusoria, and to justify their being 

 placed in the family Monadina. Four species are known. 



D. glohdm ( Volvox globulus, M.y Form subglobose or ovate ; fran- 

 sparent as water ; easily known by its tedious rolling motion ; mouth 

 not discerned. Found in salt water. Size 1 -860th. 



