Peridinaea.] THE INFUSORIA. 247 



(0). Wreath Animalcules, without horns. PEBIDINIUM. 



370. PERIDINIUM cinctum (Vorticella cincta, M.) The 

 green Peridinium is nearly globular, or slightly three-lobed 

 and smooth, with a zone of cilii ; it is not luminous at 

 night. It swims slowly, with a vacillating and rolling 

 motion. Found amongst conferva. Size l-570th. 



371. PERIDINIUM pulvisculus. The dust -like Peridinium 

 is small, of a brown colour, and not luminous at night ; 

 the lorica is almost spherical, or slightly three-lobed, and a 

 delicate proboscis may be observed, as well as nume- 

 rous stomach-cells, by feeding it on indigo. Found 

 with Chlamidomonas pulvisculus. Length 1 -2300th to 

 l-1150th. 



372. PERIDINIUM fuscum. The yellowish-brown Peri- 

 dinium is not luminous at night ; the lorica is oval, slightly 

 compressed, and pointed anteriorly. Length 1 -430th to 

 l-280th. 



(#). Wreath Animalcules, with horns. CERATIUM. 



373. PERIDINIUM (t)pyrophorum. The flint Peridinium 

 has an ovate spherical lorica, having two little points at its 

 anterior extremity. It is very delicately urceolated and 

 granulated. Found fossil in the flints of the chalk forma- 

 tion at Berlin. Size l-570th to l-480th. 



374. PERIDINIUM (?) Delitiense. The Delitzsch Peridinium 

 has an ovate spherical lorica, and laterally a little stiff 

 point near the middle. Found fossil in the flints of 

 Delitzsch. Size l-430th to l-280th. 



375. PERIDINIUM acuminatum. The pointed Peridinium 

 is of a brownish-yellow colour, has an ovate spherical 



