94 



THE AMERICAN MONTHLY 



[Maj^l 



Individuals living free, with 



one flagellum (or none) 

 on anterior end of the body 

 somewhat lateral, 

 two flagella 



one in front, one behind, 

 both in front, 



both alike, swinging, 

 dissimilar, one swinging, one trailing, 

 four flagella 

 Individuals in spherical families 

 in shrub-like families 



1. Genus, Monas. Miiller. Most 

 of the species heretofore placed in 

 this genus, (and in Bodo, Ehr.) 

 cannot now be regarded as perfect 

 organisms. The smallest of all 

 forms {Monas crepusculum, Ehr.), 

 is not to be distinguished from the 

 Sphserobacteria {Micrococcus, Hal- 

 lier, Cohn) , in part it may be also 

 minute, unorganized particles of 

 plasma. Its minute size {M. Cre- 

 jpusculum measures only 0.0005), 

 greatly increases the difficulty of 

 its study. All liquids that contain 

 decomposing organic matter swarm 

 with it. bther common forms 

 are : 



M. termo, Ehr. Colorless, sphe- 

 rical, 0.001 d., movement rapid. 



M. guttula,YhY. 0.002. 



M. lens, Duj. 0.005 — 0.014, 

 round or disc-like, very common. 



M. socialis, Ehr. 0.013. Elong- 

 ated, conical. 



M. flavicans, Ehr. Elongated, 

 oval. 



M. spiralis, Perty. Similar to 

 M. lens, but screw-like, and turn- 

 ing while swimming. 



2. Gen. Chilomonas, Ehr. Fla- 

 gellum, issuing somewhat laterally 

 from a border near the anterior end 

 of the body. 



C. paraniecitim, Ehr. Elongated, 

 oval, slightly three-sided, 1. 0.024. 

 Abundant in bread-infusions. (Ehr.; 

 compare Cryptomonas polymor- 

 jphcL). 



C. destruens, Ehr, L. 0.026, pear- 

 shaped, yellowish. In dead rotifers. 



Monas. 

 Chilomonas. 



Cercomonas. 



Amphimona. 



Heteromita. 



Tetramitus. 



Uvella. 



Anthophysa. 



3. Gen. Cercomonas, Y>vc\^. Only 

 differs from Monas by having a 

 second flagellum behind.. Dujardin 

 makes 12 species, Perty 11, of 

 doubtful value. The most common, 

 seem to be : 



C. truncata, Duj. L. 0.01. In 

 water containing bunches of flowers 

 and in other infusions. 



4. Gen. Amphimonas, Duj. 

 Body with two flagella in front, 

 one or both thrown back laterally 

 somewhat, to small projections. 



A. candata, Duj. {Bodo saltans y 

 Ehr. ?) 0.01—0.02." In infusions. 



5. Gen. Heteromita, Duj. Body 

 with two long, fine flagella in front, 

 one of which vibrates, the other 

 trails ; several vacuoles, of which 

 usually only one or two are plainly- 

 visible ; a distinct nucleus in the 

 middle, and numerous granules in 

 the hinder part. Multiplication 

 takes place by oblique division, into 

 four new individuals ; after the old 

 form has come to rest, and its outer 

 body-covering, with the old flagella 

 dissolve into a soft gelatin. Move- 

 ment takes place long before the 

 new individuals separate. The 

 animal is not destitute of a cover- 

 ing, and is, therefore, properly a 

 cryptomonadine. {Anisonema aci- 

 nus is very similar to it, but has 

 much thicker and shorter flagella, 

 one of which always trails). 



H. Ovata, Duj. {Bodo grandisy 

 Ehr.) Body egg-shaped, attenuated 

 in front, 0.027—0.035 1. Among 

 water plants, also in old water (soap 



