208 



Tetrasporineae 



The genera are : Cheetopeltis Berthold, 1878 [inclus. M^/J-I >,-/>, -rtc Bohlin, 1894] ; 

 Chsetosphseridium Klebahn, 1892 ; Dicoleon Klebahn, 1893 ; Conoch&te Klebahn, 1893 ; 

 Diplochsete Collins, 1901 ; Polychxtophora W. & G. S. West, 1903 : Oligochsetophora 

 G. S. West, 1911. Nordstedtia Borzi (1892) is a doubtful genus. 



Some of the above genera have been regarded by various authors as reduced forms of 

 the Ulotrichales. Their habit as colonial unicells and their methods of multiplication do 

 not, however, lend much support to the view that they have originated from filamentous 



Fig. 136. A and B, Ch&tosph&ridium Pringsheimii Klebahn. C, Ch. Pringsheimii var. 

 depressum G. S. West. D, a form of Coiiochsete comosa Klebalin. ch, chloroplast ; o, oil- 

 globule. E I, Oligochsstophora nhnplc.i- G. S. West ; I, cell stained to show nucleus () 

 and starch-grains (s). A D, x 430 ; E I, x 330. 



forms. On the other hand, the sheathed bristle such as occurs in Chgetosphasridium, 

 Conocheete and Dicoleon is known elsewhere only in Coleochaste, the highest type of the 

 Ulotrichales ; and the curious unattached zoosporic forms of Coleochaste recently described 

 by Lambert ('10 B), in which the thallus is reduced to a few irregularly grouped cells, 

 might be said to throw light on the possible origin of the above-mentioned genera. There 

 is, however, no evidence to show that the sheathed bristle is of any phylogenetic importance, 

 and unsheathed bristles have certainly been developed independently in several groups of 



