Suborder Chromulinineae 



Of the 2 families in this group only the Mallomonadaceae is rep- 

 resented in our collections. The Chromulinaceae includes forms 

 which have the cell membrane undecorated. They are undoubtedly 

 of wide occurrence but as yet have not been reported from this 

 region; at least Chromulina Cienkowski may be expected here. 



FAMILY MALLOMONADACEAE 



Plants solitary or colonial; cell membrane decorated or beset with 

 silicious plates or scales and bristles which may be very long and 

 sometimes irregularly diverging from the cells. 



Key to the Genera 



Unicellular, the membrane covered with variously shaped scales, 



usually bearing long needle-like bristles ...Mallomonas 



Colonial, the cells furnished with 2 long 



anterior rods set in basal cups Chrysosphaerella 



MALLOMONAS Perty 1852, p. 170 

 Unicellular, free-swimming, ovoid, elliptical, fusiform, or somcr 

 times nearly cylindrical, the membrane beset with closely arranged 

 or overlapping sihcious plates (scales) which may bear very long, 

 slender needles of the same material (also, in some species, with 

 spines near the poles of the cell); scales circular, elliptic, ovoid or 

 polygonal; chromatophores, 2 golden-brown parietal plates; 1 an- 

 terior flagellum; food reserve in the form of leucosin, which collects 

 in the posterior end of the cell. 



See Conrad ( 1927, 1933 ) for monographic treatment of this genus. 



Key to the Species 



1. Cells with an apical corona or collar .__ 2 



1. Cells without an apical corona or collar _ 3 



2. Cells with an apical collar, the margin smooth M. urnaforinis 



2. Cells with an apical corona of sharply pointed teeth M. pseudocoronata 



3. Setae arising from over the entire surface of the cell 4 



3. Setae lacking or arising from near one end of the cell - 6 



4. Cells pyriform, narrower at the anterior end- — - M. fastigata 



4. Cells ovoid or ellipsoid - 5 



5. Setae projecting at all angles, not recurved at the tips, 



cells narrower at the posterior end - M. caudata 



5. Setae mostly directed posteriorly, the tips recurved, 



cells narrower at the anterior end - — -M. acaroides 



6. Long setae not present - M. elliptica 



6. Long setae present - ' 



7. Setae few in number, sparsely scattered posteriorly; scales longi- 

 tudinally elliptical; cells 50-92/. long M. apochromatica 



7. Setae many; cells smaller ^ 



[370] 



