MASTIGOPHORA 



35 



D. sertularia Ehr. (Fig. 41). Shell .04 mm. long: in fresh water, 

 often in great quantities; sometimes fouls the water in reservoirs and 

 ponds. 



2. MALLOMONAS* Perty. Free-swimming and solitary, with closely 

 fitting reticulated oval shell bearing long spines; 2 yellowish chromato- 

 phores; without eye-spot; 1 flagellum: several species in fresh water, 

 which may produce an odor and injure water supplies. 



M. punctifera (Ehrenberg). Spines all over shell; length .035 mm. 



3. SYNTJRA Ehrenberg. Swimming spherical colonies of about 50 

 radially arranged individuals; each individual with 2 flagella, 2 brown 

 chromatophores, eye-spots and sometimes spinose: 1 species. 



S. uvella Ehr. (Fig. 42). Length of individual .03 mm.: in fresh 

 water. 



4. UROGLENA Ehrenberg. Swimming spherical colonies composed 

 of many individuals in a jelly; individual pear-shaped, with 2 unequal 



Fig. 41 



Fig. 42 



Fig. 43 



Fig. 41 Dinobryon sertularia (Conn). Fig. 42 Synura uvella (Conn). 

 Fig. 43 Uroglena americana (Calkins). 



flagella, 2 yellow chromatophores, and an eye-spot: 2 species; in fresh 

 water. 



U. americana Calkins (Fig. 43). Length of individual .006 mm.: 

 the cause of the fishy taste of the water in some reservoirs. 



FAMILY 2. CRYPTOMONADIDAE. 



Body with a firm cuticula and not amoeboid ; 2 equally long flagella, 

 at the base of which is a long pharynx extending to the middle of the 

 body; 2 chromatophores present or absent: 3 genera. 



Key to the genera of Cryptomonadidae: 



Oj Without chromatophores. 



&! A row of highly refractive bodies in forward part of body. . .1. CYATHOMONAS 

 6 2 Without such bodies 2. CHILOMONAS 



o 2 With chromatophores 3. CBYPTOMONAS 



* See "Note on the Vertical Distribution of Mallomonas," by G. C. Whipple and 

 H. N. Parker, Am. Nat, Vol. 33, p. 485, 1899. 



