Peridinaea.'] infttsoeiai animalcules 513 



T A^TOTUicwfTM volvox f Leucophri/aviridtn, M.) — Body ovate, spherical , 

 of a green colour. Found in brackish water. Size 1 -860th. 



P. Lagenula. — Body ovate, equally rounded at the two ends, and 

 having the anterior ciliated portion produced in the form of a neck 

 or beak. Found amongst Conferva. Size l-1080th to l-570th. 



Genus Chaetomonas. Tlie bristle Monad Animalcules. — Oral cilia 

 vibratory ; motion slow, and leaping by means of the bristles on the 

 body, which are not vibratile. Yery little is known of their organiza- 

 tion. They are parasites, living on the dead bodies of other Infusoria, 

 and in infusions of flesh or of animal matter. Whether the delicate 

 vibration seen at the mouth is produced by a proboscis or by cilia, is 

 uncertain. In C constricta, transverse self-division is thought to 

 have been seen. 



C. globulus is almost spherical, of an ash colour, and possesses setae, 

 or bristles. This animalcule has often the figure of Monas guttuJa, 

 though the latter is smaller ; sometimes two cluster together. Found 

 in bad smelling infusions of animal matter along with Pantotrichum 

 Enchelys, Monas termo, &c. ; also in the dead bodies of Closterium 

 aeerosum, as shown at fig. 113, which represents part of the latter, 

 with several animalcules ai'ound it. Size 1-2 8 80th. 



C. constricta is transparent, oblong, slightly constricted at the 

 middle, and having two setae, or bristles. Found in dead Hydatina 

 senta. Size l-5760th. 



Family.— PEBIDIN AE A. 



Comprehends vibrating animalcules, distinctly or apparently poly- 

 gastric, devoid of an alimentary canal, covered witli a shell, or lorica, 

 upon which, or upon the body, are cilia or setae : these are often 

 arranged in the form of a girdle or crown — hence the name. The 

 lorica has only one opening. In three out of the four genera an 

 organ of locomotion is present, in the form of a dcHcate proboscis, 

 independent of the wreath of cilia around the middle of the body, or 

 scattered cilia or biistles. In onljPeridiniumpulvisctdus and P. cinctum 

 have artificial means succeeded in demonstrating the nutritive appa- 



