On South African Paramphistomidae (Fisch.). 183 
tion of Isidora tropica in a restricted locality in what is locally known as 
the Stellenbosch Flats, situated in the town commonage. From previous 
observations carried out on the occurrence of rediae and cerceriae in fresh- 
Fig. 3. Fig. 4. 
water snails from that particular locality., I knew that the snails harboured 
small black cerceriae in abundance. These cerceriae readily encyst on 
the grass stems growing round and in the pools of water, and thus easily 
reach the stomach of sheep and cattle that graze on the commonage. 
Animals that had grazed on the commonage were found to be heavily infected 
