24 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [BuU 



mass. Individuals like Dinohryon, usually with two yel- 

 low chromatophores and an eye-spot. Nuclei central and 

 an anterior contractile vacuole. One primary and one 

 secondary flagellum. 



U. americana Calk., Fig. 49. The cause of a fishy taste 

 frequently found in reservoirs. 

 Mallomonas Perty. 



Oval to enlongated, solitary, with a shell made up of 

 overlapping plates bearing long spines. One prominent 

 flagellum. Two yellowish green chromatophores, but no 

 eye-spot. Many posterior contractile vacuoles, and an 

 elongated anterior nucleus. 



M. acaroides Perty, Fig. 58. 



M. sp ( ?), Fig. 60. Cross section. Fig. 60a. 



. SUB-ORDER EUGLENOIDINA 



Key to Genera. 



I. One evident flagellum (two similar flagella in Eu- 



treptia) 2 



One chief and one secondary flagellum 15 



Typically colored 3 



Typically uncolored 12 



3. Naked, or with very thin cuticle 4 



With cuticle usually striated ; flexible or rigid ; some- 

 times with lorica or shell 7 



4. Numerous small green chromatophores 5 



Two yellow or green chromatophores 6 



5. Without trichocysts Ccclomonas 



With trichocysts Gomostomum 



6. Two lateral brown chromatophores, each with one 



eye-spot; mouth opening and vacuole system 



present Microglena 



One or more yellow chromatophores; one eye-spot 

 and many contractile vacuoles at base of flagellum 



Chromulina* 



Two green chromatophores ; one eye-spot 



Cryptoglena* 



7. Flexible ; free swimming, with a delicate shell, or 



fixed in a lorica, or on a stalk 8 



