242 C. CLIFFORD DOBELL. 
oval (fig. 38, Pl. 3), are shghtly yellowish, and contain a 
single individual. The axostyles are not as a rule very dis- 
tinctly seen, and there are no flagella present. 
Ona single occasion I have seen a cyst containing a monad 
which had become motile, having eight flagella, inside its 
cyst (fig. 39). After moving about actively, stretching the 
cyst in all directions, the monad subsequently escaped and 
swam away. 
As in the case of the trichomonads, I have absolutely no 
idea what the influence is which causes the animals to encyst. 
Temperature, nutrition, drying, etc., appear to take no part 
in bringing about encystment. 
Regarding sexual phenomena, I can merely repeat that I 
have never seen any conclusive evidence that conjugation 
takes place. Prowazek has stated that conjugation (hetero- 
gamy) occurs in ‘‘ Hexamitus intestinalis” from Tes- 
tudo greca, but I cannot regard it as proven. ‘The conju- 
gation is said to be similar to that of Trichomonas. It may 
be added that Wenyon’s careful investigation of similar 
forms in the rat resulted in observations similar to mine— 
namely, the discovery of monozoic cysts without any trace of 
conjugation. 
(3) Monocercomonas bufonis Dobell. 
On two occasions I have encountered in the toad a quadri- 
flagellate parasite, which differs considerably from T'richo- 
mastix. Although rare, the organism was present in great 
numbers in the infected animals. These, it may be noted, 
were both captured in the same place. 
I have referred the animal to the genus Monocerco- 
monas Grassi, because I believe the genus Tetramitus, to 
which similar organisms belong, ought to be reserved for 
free-living forms. And although the genus Monocerco- 
monas is not very well defined,! it has already been used for 
1 The type-species is probably Monocercomonas melolonthe, 
but Grassi’s descriptions and figures are not easy to deal with. He has 
variously given Trichomonas (1879) and Trichomastix (1888) as 
synonyms for Monocercomonas. 
