02 VERMES. 



Class III. Rotatoria (Rotifera). Wheel 

 Animalcules. 



Small unsegmented aquatic animals. Possess a retractile trochal 

 apparatus, a single cerebral ganglion, and two excretory tubes opening 

 into an archiccelic body-cavity ; sexes separate. No vascular system. The 

 male smaller, mostly with a cord-like rudiment of the gut, and mouthless. 

 Summer eggs (parthenogenetic), and winter eggs (fertilized). Rotifer 

 vulgaris (redivivus), trochal disc double. Brachionus with carapace. 

 Hydatina senta. Pedalion, with limb-like appendages. 



Here may be annexed the Gastrotricha, with ciliated ventral surface. 

 Chaetonotus. 



Ray Lankester includes Rotatoria (on the strength of Pedalion), Chtetopoda, 

 and Arthropoda, in a single phylum, Appendiculata, characterized by the pos- 

 session of lateral locomotor appendages. TR. 



