Ichthydina.'] T HE INFUSORIA. 331 



truncated, cylindrical, false foot. The rotatory organ is 

 also simple, and nearly circular. Numerous teeth-like 

 bodies, adhering to the bulb of the oesophagus, two pan- 

 creatic glands, a small narrow oesophagus, an elongated 

 stomach, and a globular-like rectum, are the apparatus of 

 nutrition. An ovarium and a contractile vesicle have been 

 observed, but neither longitudinal muscles nor visual or- 

 gans, although carefully sought for. 



563. PTYGURA melicerta. The wrinkled-tail Ptygura. 

 Transparent, body cylindrical, club-shaped, turgid ante- 

 riorly, with two little curved horns at the mouth, and a 

 single short tube at the neck (?). The tail-like foot always 

 remains transversely folded (wrinkled), as seen in Jig. 354, 

 plate vii. 5 which represents the under side. When swim- 

 ming, a ring-like simple vibratile organ is thrust out with 

 a lateral notch. The two jaw-like parts of the oesophagal 

 bulb have numerous teeth, as represented at Jig. 355. 

 Size l-140th. 



Genus CXXXV. ICHTHYDIUM. The ciliated Jish Animal 

 cules have a cleft or forked foot-like tail, no eyes or hair ; 

 currents at the mouth, and along the ventral side, indicate 

 the existence of a vibratile organ, which not only serves for 

 swimming, but likewise for creeping. A long oesophagus, 

 a thick simple conical alimentary canal, and sometimes a 

 large single ovum, comprise our knowledge of their organi- 

 zation. It is probable that a cylinder of little wand-like 

 teeth exists. 



564. ICHTHYDIUM podwra (Cercaria podura, M.) The 

 ciliated Ichthydium. Body straight, oblong, often slightly 

 constricted anteriorly, which is turgid, and sometimes three- 

 lobed. It is colourless or whitish, but during repletion 



