CILIOPHORA, CI LI AT A, PROTOCILIATA 



337 



which are invariably in a stage of mitotic division, are con- 

 spicuously present. In the rectum of various species of Am- 

 phibia with one exception. 



Protoopalina intestinalis (Stein) (Fig. 144, a-e). In the in- 

 testine of various species of frogs and toads. 



Protoopalina saturnalis Leger and Duboscq (Fig. 144,/, g). 

 In the intestine of the marine fish, Box boops. 



Protoopalina mitotica (Metcalf) (Fig. 145, a). Body 300 

 microns long by 37 microns broad. In the intestine of Amby- 

 stoma tigrinum. 



Fig. 145 a. Protoopalina mitotica. X150. 



b. Zelleriella scaphiopodos. X150. 



c. Cepedia cantabrigensis. X150. 



d. Opalina hylaxena. X150. 



e-m. 0. obtrigonoidea. X^O. e-i, irom Bufofowleri; 

 j-m, from Rana pipiens. (All after Metcalf). 



Genus Zelleriella Metcalf. The body is greatly flattened. 

 Two similar nuclei which are in a mid-mitotic condition. All 

 in Amphibia. 



Zelleriella scaphiopodos Metcalf (Fig. 145, b). In Scaphiopus 

 solitarius. Body about 150 microns long by 90 microns broad 

 by 13 microns thick. 



Genus Cepedia Metcalf. The body is cylindrical or pyriform 

 as in Protoopalina, but contains many similar nuclei. All 

 in Amphibia. 



