302 DESCRIPTION OF [Poh/gastn'ca. 



verse, self-division. Found both in fresh and salt water. 

 Size 1-1 150th to l-140th. 



496. Chilodon uncinatus. The hook Chilodon has a 

 depressed oblong body, rounded at the ends. The right 

 side of the anterior part is produced, so as to appear like 

 a hook or beak. Found in vegetable infusions. Size 

 l-430th. 



497. Chilodon aureus. The gold-coloured Chilodon 

 has an ovate, conical, turgid body, of a golden yellow 

 colour, dilated and obtusely rostrated anteriorly, attenuated 

 posteriorly. Size 1-1 40th. 



498. Chilodon ornatus. The adorned Chilodon has 

 an ovate sub-cylindrical body, of a golden yellow colour, 

 equally rounded at both ends, slightly beaked j it has a 

 bright violet spot. Size 1-1 80th. 



Genus CVII. Nassula. The wheel Animalcule. — Body 

 covered with cilii, turgid and prominent in front, but 

 without the expansion or beak on one side ; mouth provided 

 with a circlet of teeth, in the form of a wheel (Nassa). 

 Numerous polygastric cells are seen, and in two species the 

 discharging orifice. Ehrenberg states that the existence of 

 a new system of organs subservient to digestion becomes 

 evident in this genus : these are of a violet colour, and pro- 

 bably biliary glands ; one is present in Chilodon ornatus 

 and chlamidodon, Bursaria vernalis, Trachelius meleagris, 

 Amphileptus margaritifer, meleagris, and longicoUis ; they 

 resemble the vesicular glands around the stomachs of the 

 Rotatoria. The propagative system is double; two species 

 have the ova granules, and all possess a large oval or 

 spherical gland, and one or more contractile vesicles. 

 Transverse self-division onlv has been observed. 



