Oxi/trichina.] infusorial akimalctjles. 595 



structure ; the mouth, aud probably the anal spot, are upon the 

 veutral surface. The propagative system is double, consisting of 

 ova glands, and a contractile vesicle. Self-division has not been 

 observed. 



In this genus Kerona, Dujardin also includes the Stylonychia of 

 Ehrenberg, not considering the slight difference in their appendages, 

 suJ9Sciently distinctive to separate them into two genera. 



The Kerona thus understood, differ from Oxytricha only in the 

 form of their cirrhi or processes, the base of which is commonly 

 dilated in the form of a transparent ball, and moveable withal. 

 They are, however, equally voracious and abundant in stagnant 

 water and infusions. 



Kerona pustulata, (Duj.) = Stylonycha pustulata, (Ehr.,) 

 K. histrio = S. histrio ; K. mytilus = /S. mytilus. But K.pullaster 

 "would rather seem analogous to Oxytricha pullaster, (Ehr.) 



The only species of Kerona mentioned in Dujardin's work, and 

 not included in that genus, or in Stylonychia by Ehrenberg, are — 

 Kerona calvitium, and Trichoda faveata of Miiller, two names 

 indicating varieties of the same species, which varies in the number 

 and size of its appendages. It is oblong, with styles projecting 

 anteriorly; flattened and obtuse at each end. 



Kerona polyporum. — Body whitish, depressed, elliptical, and 

 reniform ; it has a series of cilia around the frontal region, produced 

 from below the mouth ; Ehrenberg counted above forty digestive 

 cells, many of them filled with brownish (half-digested green) 

 Monads. Between the cells are ova granules. Fig. 340 is a back 

 ■view, and fig. 3-11 a side view, climbing. Parasitic on Hydra vulgaris. 

 \See 'Microscopic Cabinet,' pi. 7.) Animals infested with them 

 die. Size l-144th. 



Genus Ukostyla. — The style Animalcules are provided with cilia 

 and styles, but are destitute of uncini; the cilia are thickly disposed in 

 numerous series, those near the mouth being longest. On the 

 ventral surface, at the posterior end, is a small cleft, provided with 

 non-vibratile setse. The numerous digestive cells receive colour and 

 large bodies ; a gland, a contractile sexual vesicle, and delicate 

 granular ova, represent the propagative system. Transverse self- 

 division also has been observed. 



