CHLOROPHYCE^ 161 



with no cross-walls, giving off rhizoids below and 

 dichotomous branches above. Chamacdoris has a 

 similar stalk, with its branches given off in a great 

 terminal tuft in habit like Penicillus in this respect. 

 It appears very probable that the stalk is persistent 

 and renews its crop of branches, both in this genus 

 and at all events in some of the species of Struvea. 



The large species of Struvea are among the most 

 beautiful of Algae. At the summit of the long 

 rugose stalk without cross- walls there is borne a flat 

 frond, through which the stalk is prolonged as a 

 mid-rib. This mid-rib gives off opposite branches, 

 which are again pinnately branched, and in some 

 species these are similarly branched again and again. 

 Where these pinnae meet they are all bound by 

 sucker-like haptera (Fig. 48e), and the frond presents 

 the appearance of a lovely piece of lace. S.plwmosa, 

 S. macrophylla, and S. pidcherrima are the largest and 

 finest species. Only three specimens of S. macro- 

 phylla have been found, two of them being in the 

 herbarium of Trinity College, Dublin, and one in the 

 British Museum. S. pulcJicTrima is even more rare, 

 one specimen, not quite complete, being in the 

 British Museum, and a fragment in the Edinburgh 

 herbarium collected at the same time. The more 

 slender forms have stalks unmarked by rugosities. 

 The forms described as species of Spongocladia were 

 long puzzling. They are dense wefts of interwoven 

 filaments, with walls so much thickened in places as 

 to obliterate the cell-lumen. They grow in intimate 

 association (Symbiosis) with sponges, and assume to 

 some extent the habit of these animals. It has 



M 



