38 



INVEUTEBKATE ANIMALS. 



of cilia. There is a thii'd smuller group — tlie Suctoria — in which 

 the body is furnished with contractile tentacle like filaments, which 

 end in little discs, and are used as sncking-tubes. It will not be 

 necessary to do more than mention the Suctorial Infusoria here ; 

 but the two groujjs of the Ciliata and Flarjellata require more 

 detailed attention. 



Fi^. 17.— Ciliati;il and Flagell.ite Infusoria. A, Bursaria Iruncatella, enlarged 50 

 tiiiii-s. B, NyrJolhenis conU/ormis, enlarged 130 times. C, AmpMlepiiis anser, 

 enlarged 120 times. D, CenUimn tripos, enlarged 250 times, with its carapace and 

 single Ilagellum. E, Monosiga angustata, enlarged 2-')00 times : n Nuelens ; c 

 Ccintr.actile vesicle; / Flagellmii ; m Membranous collar surrounding the liase of 

 the flagelluui, (After, or copied froui, Saville Kent.) 



The CUiated Infusoria may be defined as Protozoa which are -pro- 

 vided with a month, and iixiin/tij a short gullet and a distinct anus. 

 Their liodie.1 consist of soft scmi-tluid protoplasm {'' endoplasm ") (H- 

 closfxl hy a more or less comiiJe.e external layer ('' e.voplasm") ; and 

 the e.rternal surface is partly or leholly corered with vihratimj cilia. 

 They lire mostly simiJe free-swimming organisms ; but they some- 

 times form colonies by budding, and are fi.xed to some solid object 

 ill thoii' adult ci.uditioii. As tyjjes of these two sections of the In- 

 fusoria, we may take rcs;icci;ve'y I'arameecium and Vorticelia. 



