PI. ATE XX. 



Metopides acuminata, x 620, 

 Spirostomuin ambigmon, x 50, 

 Spirostonium ambigimm, contracted, x 70, 

 Spirostonium teres, x 180, . . - 



Condylostoma sp., x 500, . . - 

 Unidentified sp., X 310, - -. - 



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