PLATE XI!. 



Class ROTIFERA. 



THE WHEEL- ANIMALCULE (Rotifer vulgaris). 



FlG. 1. EOTIFEll: WITH DISC EXPANDED. X 4 . 



d. trocbal disc or wheel organ : e. eye : s. siphon : /. jaws with teeth : 

 a. c. alimentary canal with g. glandular mass surrounding it : 

 t. tube of the water vascular system : c. cloaca : /. foot portion. 



. 2. IlOTIFER : WITH DlSC RETRACTED. X 4 . 



m. mouth : e. eye : d. trochal disc or wheel organ : /. jaws with teeth : 

 a. c. alimentary canal with g. glandular mass surrounding it : 

 t. tube of the water vascular system: c. cloaca: /. foot 

 portion. 



Class-GEPHYBEA. 



Sipunculus. 



FIG. 3. SIPUNCULUS : WITH MOUTH PARTLY RETRACTED, x 1. 



m. position of the mouth : r. m. retractor muscles of the mouth : 

 r. nerve ring : n. ventral nerve cord : i. intestine : a. position 

 of the anus : I., b. " brown tubes." 



