158 University of California PuhUcaiions in Zoology [Vol. 20 



microfauna of that habitat, it is obvious that Miiller (1773), Mandl 

 (1838-1845), and Moquin-Tandon (1860) may have been dealing with 

 that flagellate. 



However, Miiller 's figures are so imperfect and his description so 

 meagre that there is no certainty whatever that he had a Trichomonas 

 and there is still less a clue to the specific identity of the moving 

 organism he discovered. It may well be that with additional investi- 

 gation more than one kind of flagellate will be found in the mouth. 



In view of the lack of critical evidence we reject Jliiller's Cercaria 

 tenax as unidentifiable with Tetratrichonionas buccalis Goodey and 

 Wellings and as an indeterminable species. The specific name tenax 

 is therefore not available and Trichomonas buccalis (Goodey and 

 Wellings) becomes the correct name for the trichomonad flagellate of 

 the mouth. 



It is possible that the trichomonad of the lung and that of the mouth 

 belong to the same species, but this is not as yet proved and Tricho- 

 monas pulmonalis Schmidt (1895) is so inadequately characterized as 

 to be unidentifiable. As described it cannot be distinguished from 

 T. intestinalis and T. vaginalis, and the specific name pulmonalis 

 should be allowed to lapse as indeterminable. 



One factor complicating the status of these several species is the 

 question as to the number of flagella which in the earlier accounts 

 (Davaine, 1854, 1860, and others) was reported as one, and in others, 

 such as Kunstler (1898), as varj'ing (in Trichomoyias of the rat) 

 from 4r-8-10 up to 15, while in recent years Wenyon and O'Connor 

 (1917) admit that there are forms with three, four, and five flagella. 



The uncertainty as to the number of flagella in both T. vaginalis 

 and T. hominis is shown by Doflein's (1916) cautious treatment of 

 this matter. He regards three flagella as typical and four as possibly 

 resulting from the detachment of the marginal filament of the undulat- 

 ing membrane, and a resulting "Trichomastix" condition which has 

 four free flagella, one of them trailing. This conclusion appears to 

 me incorrect, after a review of the literature, and careful examination 

 of my own preparations and cultures and of other preparations secured 

 from Drs. Lynch, E. L. "Walker, and F. G. Haughwout. In every 

 instance where the number of flagella can be accurately determined 

 we have unquestionably found four anterior flagella and an undulating 

 membrane with marginal filament present in both T. hominis and 

 T. vaginalis. 



There is a tendency for the flagella of Trichomon^is to adhere to 

 one another in a single strand, parting only distally. Often only three 



