It is these which afford the justification for any comparison between Sinocystis and Megacystis. Those of Sinocystis are, it will be remembered (antea, December, 1918, p. 534), a transversely elongale peristome, a hydropore-slit approximately parallel to the peristome, a gonopore to the left of the anal plane, and a hexagonal or pentagonal periproct. These openings, though differing in details, are in number and position essentially similar to those of Aristocystis. Hitherto there has been much uncertainty as to the positions, and even the presence, of the hydropore and gonopore in Megacystis. It will here be shown that both are present, and that all four openings have much the same relations as in Aristocystis and Sinocyatis, especially the latter.