102 DESCRIPTION OF \_Polygastrica. 



increase by ova. These characters are sufficient to distin- 

 guish them from all other Infusoria, and to justify their 

 being placed in the family Monadina. Four species are 

 known. 



38. Doxococcus globulus (Volvox globulus, M.) The 

 globular Doxococcus. Form subglobose or ovate; tran- 

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

 mouth not discerned. Found in salt water. Size l-860th. 



39. Doxococcus ruber. The red Doxococcus. Form 

 globular ; colour brick red, opaque. Ehrenberg appears to 

 doubt whether this animalcule holds its proper situation 

 here, or whether it should be placed with the genus Tra- 

 chelomonas, though its motion is very peculiar ; and he has 

 not been able to satisfy himself of the existence of a lorica, 

 or shell, enveloping the creature. Group 18 represents 

 three magnified individuals. Found amongst conferva, 

 &c. Size 1-1 720th. 



40. Doxococcus pulvisculus. The Green Doxococcus. 

 Form perfectly (?) globular ; colour green, but opaque. 

 Found amongst conferva. Size not exceeding 1-1 280th. 



41. Doxococcus inequalis. The irregular-shaped Doxo- 

 coccus. Form irregularly globular ; transparent, and 

 covered with green spots. Found amongst conferva. 

 Size l-2400th. 



Genus VIII. CHILOMONAS. The lip-Monads constitute 

 but a small genus. They are characterized by the oblique 

 position of the mouth, with respect to the longitudinal axis 

 of their bodies, which occasions an overhanging or pro- 

 jecting form above the mouth, of a lip -like appearance. 

 All the species propel themselves in the direction of the 

 long axis of the body. Their form is invariable, and they 



