224 J- McA - KATER. 



tinction of leading the family in this respect. Astermonas was 

 the last holophytic genus described (Artari, 1913). 



Dangeard instituted this family to include holophytic, uni- 

 cellular algae and all of the species mentioned above would fit in 

 with that scheme. They possess a chloroplast, a pyrenoid for the 

 formation of starch, and a red pigment spot may or may not be 

 present. In Dunaliella the green is sometimes obscured by 

 another pigment which gives the organism a vermillion color. 



A phylogenetic series might be made, beginning with the six or 

 eight flagellated Polyblepharides, going through the five flagel- 

 lated Chloraster, Pyramimonas, which possesses four flagella, 

 Stephanoptera, with two flagella, and culminating with the bi- 

 flagellate Dunaliella, the nearest approach to Chlamydomonas. 

 With the exception of Dunaliella all species have four longitudinal 

 ridges. One might suggest that the scheme could be arranged in 

 the opposite direction, but since the specialization of the Chla- 

 mydomonad type is much greater than that of the Polyble- 

 pharididae this order seems the more reasonable. 



In 1910 Aragao described Polytomella agilis and suggested that 

 ts relationship was with the Protomonads. Doflein (1916) 

 demonstrated the presence of starch in the same species and 

 consequently, reclassified it under the order Phytomonadina, and 

 since its pellicle divides at fission its family is Polyblepharididae. 

 This colorless form, possessing four flagella, stands in the same 

 relation to Pyramimonas that Polytoma and Paraplytoma do to 

 Chlamydomonas. Dangeard 's family no longer includes only 

 holophytic algae, and the green color must be omitted from a 

 characterization of it. 



The protozoan dealt with in this paper differs from Aragao's 

 species in the following points: an eye-spot is present in agilis 

 while citri possesses no such structure; the nucleus of agilis 

 contains scattered chromatin while in citri it is concentrated in a 

 single karyosome, the four flagella of agilis arise from four 

 blepharoplasts and citri has only two basal granules. These 

 differences are not sufficient for generic distinction, but justify the 

 formation of a new species. 



It is to be regretted that so little study has been made of the 

 finer points of structure of the members of this group, the 



