102 DESCPviPTlox OF [Poly(jastrica. 



increase by ova. These characters are sufficient to distin- 

 guish them from all other Infusoriaj 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-8G0th. 



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-I720th. 



40. Doxococcus pulvisculus. The Green Doxococcus. — 

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

 Found amongst conferva. Size not exceeding 1- 1280th. 



41. Doxococcus me<^M«//5. The irregular-shaped Doxo- 

 coccus. — Form irregularly globular ; transparent, and 

 covered with green spots. Found amongst conferva. 

 Size l-240Gth. 



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 liody. Their form is invariable, and they 



