64 



YEKMES. 



which the animal can withdraw itself. Philodina, Melicerta, and 

 one or two others construct a floccose covering for their protec- 

 tion in winter. 



The Eotifers delight in the sunshine ; on a dull day they con- 

 ceal themselves. They swim either by means of their cilia, or by 

 bending the body and jerking themselves along. There are about 

 200 species, nearly all freshwater. Flosculariidae are permanently 

 fixed. Notommata parasita is an entozoon of Volvox globator. 



By some these animals are regarded as unsegmented Arthropods. 

 Ehrenberg places Ichthydiidse in this class, under his order Mo- 

 notrocha. Albertia is worm-shaped, and parasitic on Lumbricu&, 

 Nais, &c. Seison is found on Nebalia ; these two genera consti- 

 tute the Perosotrocha of Schmarda, a pendant to the Eotifers. 

 Trochosphcera, with a globular body and a ciliated girdle, is 

 another pendant. Apsilus and Balatro are destitute of vibratory 

 cilia ; they are present, however, in the young of the former. 



No intestine nor anus G-ASTRODELA. 



With intestine and anus. 

 One disk. 



Disk entire HOLOTROCHA. 



Disk divided SCHIZOTROCHA. 



Two disks .. ZYGOTROCHA. 



GASTRODELA. Flosculariidce. 



Asplanchnidce. Eloscularia. 



Asplanchna. Melicerta. 



Ascomorpha. Stephanoceros. 



HOLOTROCHA. 



ZYGOTROCHA. 



Ptygura. 

 Diplotrocha. 



(Ecistide. 

 GEcistes. 

 Conochilus. 



SCHIZOTROCHA. 

 Mega lotrochidce. 

 Megalotrocha. 



Hydatina. 



Diglena. 



Eosphora. 



Notornrnata. 



Synchgeta. 



Polyarthra. 



Apsilus. 



EuchlanidcB. 



Euchlanis. 



Stephanops. 



Metopidia. 



Philodina. 



Eotifer. 



Actinurus. 



ScaridiidcB. 

 Scaridium. 



JBrachionidoe. 

 Brachionus. 

 Anursea. 

 Noteus. 



AlbertiidcB. 

 Albertia. 



Seison = Saccobdella. 

 Balatro. 



