304 



Ulotrichales 



1899 ; Pseudendoclonium Wille, 1901 ; Zoddsea Borzi, 1906 : Endophyton Gardner, 1909 ; 

 Pseudodictyon Gardner, 1909. 



With the exception of Pseudodictyon and Endophyton, which are marine, and the brackish 

 genus Endoclonium, all the above-mentioned genera are inhabitants of fresh water. Some 

 are epiphytic (Endoderma spp., Glceoplax, Pseudodictyon, Chloroclonium\ some endophytic 

 (Endoderma spp. and Endophyton)^ and others are attached to stones or shells. The 

 latter usually develop a procumbent stratum of branches, often to some extent concrescent, 

 from which arise numerous, erect or divergent, branches (consult fig. 196 A, Z>, and F). 

 Microthamnion does not appear to be attached at any time, even though the young plants 

 have a decided basal development (consult fig. 197 A and C}. 



Trichophilus Welckeri Web. v. Bosse (fig. 195) is an endozootic Alga in the hairs of 

 Brady pus (the Three-toed Sloth), causing the fur of the animal to assume a peculiar 

 greenish tint. The growth of the Alga is greatly facilitated by the dampness of the 

 atmosphere in the gloomy forests in which the sloth lives. Trichophilus Neniae, Lagerh. 

 is epizootic on the shells of the mollusc Nenia (Clausilia). 



Fig. 198. A and B, Tellamia perforans (Chod.) Wille. A, the Alga penetrating the prismatic 

 layer of the shell of Anodonta; B, the algal filaments passing from the prismatic to the 

 nacreous layer, x about 750 (after Chodat). C E, Gomontia codiolifera (Chod.) Wille. 

 C, part of thallus with codioliform cells ; D, typical filament ; E, detached ' codiolum-state,' 

 x about 500 (after Chodat). 



Sub-family GOMONTIE^E. The Algae of this sub-family bore into the 

 calcareous shells of various molluscs, especially bivalves. There is a 

 peripheral dorsiventral thallus, with many branches more or less radiating 

 from a central point, the cells of which are both irregular in outline and 

 irregularly branched. From this part of the thallus, which in Tellamia is 

 often pseudoparenchymatous, numerous branches descend almost vertically 

 and penetrate deeply into the calcareous layers of the molluscan shell 

 (fig. 198 A and B). The cells of the more deeply penetrating branches are 



