LEE BARKER WALTON 133 



tinous like mucous covering; plane of each series of 4 cells 

 perpendicular 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/x. 



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



Habitat, surface water at margin of lake. 



The relationship of the form to Coelastrum and the 

 other allied genera of the family seems clear, although the 

 systematic position must be a provisional one until the 

 method of reproduction is known. In its organization it 

 represents the lowest form of the family v/here a definite 

 colonial organization is attained. 



Kofoid (1914) has recently described a new genus and 

 species, Phytomorula regular is, from a reservoir at Berke- 

 ley, California, which is allied to Coelastnun and is of un- 

 usual 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 presenta- 

 tion of the paper, to obtain information as to its method 

 of reproduction. 



The family Coelastridce 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 occurrence. Eutetramorus is based 

 on a single specimen obtained at Columbus, Ohio. Phyto- 

 monda is described from a very few specimens obtained in 

 a reservoir at Berkeley, California. Burkillia is known 

 only from Burma. The remaining two genera, Ccelastruvi 

 and Sorastnim are abundant and have a wide distribution. 

 The genus Hariotina based by Dangeard (1889) on H. 

 reticidafum is now included with Ccelastrum while 

 Selenosphcerimn of Cohn (1879) is placed with Sorastnim. 



