Feb., 1918] Eutetramosru Globosus 127 



is taken from a camera lueida sketch made at the time with a 

 Leitz Binocular, 2 mm. apochromatic objective. 



Eutetramorus n. g. 



Cells non-motile, light chlorophyl green; united into a col- 

 only of 16 cells arranged in groups of 4's within a gelatinous 

 like mucous covering; plane of each series of 4 cells perpen- 

 dicular to the square included by the groups. 



Represented by a single species. 



E. globosus n. sp. 



Cells spherical, containing a chloroplast with central 

 pyrenoid, the 16 cells united in groups of 4's, the distance 

 between each group and the adjacent lateral group being 

 approximately one and one-half times the diameter of the 

 individual cell; reproduction unknown. 



Diam. (single cell 5/x. (colony) 30^. 



Distribution, Mirror Lake, Columbus, Ohio (U. S. A.). 



Habitat, surface water at margin of lake. 



The relationship of the form to Ccelastriim and the other 

 allied genera of the family seems clear, although the systematic 

 position must be a provisional one until the method of repro- 

 duction is known. In its organization it represents the lowest 

 form of the family where a definite colonial organization is 

 attained. 



Kofoid (1914) has recently described a new genus and 

 species, Phytomorula regularis, from a reservoir at Berkeley, 

 CaHfornia, which is allied to Ccelastrum and is of unusual 

 interest in that it represents a 16 celled colonial form extremely 

 flattened, the cells being contiguous although not arranged in 

 the same plane. The species was extremely rare and he had 

 been unable, at the time of the presentation of the paper, to 

 obtain informa- tion as to its method of reproduction. 



The family Ccelastridce now consists of five genera which may 

 be separated in accordance with the table given below. Three 

 of the genera have an extremely restricted distribution which, 

 however, may be the result of their comparatively rare occur- 

 rence. Eutetramorus is based on a single specimen obtained at 

 Columbus, Ohio. Phytomorula is described from a very few 

 specimens obtained in a reservoir at Berkeley, California. 



