288 DESCRIPTION OF [Polygastrica. 



polygastric system of nutrition (with the anterior and pos- 

 terior orifices of the alimentary canal) has been observed, 

 by feeding on colouring matter. A long band-like gland 

 and contractile bladder, with a granulated mass, are seen 

 in P. niveus. 



457. Prorodon niveus. The white Prorodon. — Body 

 large, elliptical, and compressed ; colour white ; circlet of 

 teeth compressed, as shewn separate at Jig. 283. Found 

 amongst conferva in turf pools. Length l-72nd ; ova 

 granules 1 -2400th. 



458. Prorodon teres. The cylindrical Proi-odon. — 

 Body ovato-cylindrical, as represented at Jig. 282 ; it is of 

 a white colour, circlet of teeth cylindrical. Ehrenberg 

 counted twenty teeth; when broken up, forty-five. In 

 swimming it revolves upon the long axis of the body. Size 

 l-140th. 



