306 FAMILY: MONADID^ 



Costia. The body, which is somewhat flattened, is pear-shaped in outline 

 (Fig. 145). At the anterior pointed end is a funnel-like depression, from the 

 bottom of w^hich arise the flagella. According to Morof? (1903), there are 

 two long flagella which extend beyond the body and two short ones con- 

 fined to the interior of the funnel. It seems possible that the two short 

 flagella are new ones forming preparatory to division, and that the organism 

 has really only two long flagella. The body measures from 10 to 20 

 microns in length by 5 to 10 microns in breadth. The parts of the flagella 

 beyond the body have a length slightly shorter than that of the body itself. 

 There is a spherical nucleus at the middle of the body, while behind it is 

 a contractile vacuole. Reproduction is by longitudinal division, while 

 spherical cysts 7 to 10 microns in diameter are formed. The flagellates 

 are parasitic on the skin of fish, to which they are attached by their 

 flagella. They sometimes occur in enormous numbers on young fish 

 artificially reared, and have been suspected of causing a high rate of 

 mortality. 



C. MONADID^E WITH THREE FLAGELLA. 



Genus: Enteromonas Fonseca, 1915. 

 This genus was founded by Fonseca for a flagellate named by him 

 Enteromonas ho?ninis which he found in human faeces in Brazil (Fig. 146). 

 The various descriptions he has given of the organism are not in agreement. 

 The last account given by him (1920) describes the flagellate as having a 

 splierical body 5 to 6 microns in diameter. There was a nucleus near the 

 anterior end 1 micron in diameter. Running from the nucleus to the 

 anterior end of the body was an axoneme which terminated in a blepharo 

 plast, from which arose three flagella. There was no cytostome. The 

 cytoplasm contained food vacuoles, but no other structures. Encysted 

 forms were not encountered. Chalmers and Pekkola (1917a, 1918) re- 

 corded the finding of an organism in human faeces which they believed to 

 be identical with Fonseca's E. hominis, while Chatterjee (1917) erro- 

 neously ascribed to the genus Monocercomonas an organism with similar 

 structure from human beings in India. Later in the same year (1917a) 

 he gave an account of a new organism which he named Trichomastix 

 hominis, on account of the fact that some of the individuals had four free 

 flagella. It is very probable that the forms with four flagella were pro- 

 ducing new flagella in process of division, for, of the thirty-five individuals 

 figured, only four are shown with four flagella. All the others have three, 

 with the exception of one with two. It seems clear, therefore, that the 

 organism is not a Trichomastix (Eutrichomastix) at all, and that it is the 

 same as the form previously described by him as Monocercomonas, which 

 again appears to be identical with the forms first seen by Fonseca. The 



