EUPHYCOPHYTA 



79 



Within the Trentepohhaceae there are several genera the species 

 of which form a green discolouration on and in stones and shells 

 of gastropods. Such genera are Gongrosira and Gomontia. These 

 are very difficult to determine taxonomically. They are in need of 

 study as some, at least, may represent stages in the life history of 

 other algae. Recent work on Gomontia polyrhiza has shown that it 

 has a life cycle of a large unicell alternating with a plate-Uke disc. 



* CoLEOCHAETACEAE : Cokochaete (coleo^ sheath; chaete, hair). Fig. 

 42 



Most of the species are fresh-water epiphytes attached to the 

 host by small outgrowths from the basal walls, but there is one 

 species that is endophytic in Nitella, one of the Charales (p. 115). 



Fig. 42 Coleochaete. A, C. scutata, thallus with hairs ( x 150). B, 

 C. pulvinata with spermocarp ( x 45). C, C pulvinata with 

 antheridia (a) and young carpogonium (c). D, C pulvinata, ahnost 

 mature carpogonium. E, C. pulvinata, fertilized carpogonium, F, 

 C. pulvinata, formation of envelope around fertihzed carpogonium. 

 G, C. pulvinata, mature spermocarp with carpospores. (A, B, after 



Smith; C-G, after Fritsch.) 



Some of the species are truly heterotrichous whilst others only 

 possess the prostrate basal portion, which is either composed of 

 loosely branched threads or else is a compact disc. The growth of 

 the erect filaments is by means of the apical cell whilst the basal 

 cushion possesses a marginal meristem. Each cell contains one 

 chloroplast with one or two pyrenoids, and although a character- 

 istic sheathed bristle arises from each cell nevertheless in the old 



