Ulvacece 



97 



(fig. 35, A K). In the former species the cells are rounded, 612 p in 

 diameter, and arranged in fours, the two pairs often being disposed in a more 

 or less T-shaped manner. In the latter species the cells are much more 

 compact, angular, and 8 20 p. in diameter. 



Fig. 35. A K, Monostroma membranacea West & G. S. West, from Mitcham 

 Common, Surrey. A, nat. size ; B and C, portions of thallus showing cells ; 

 D, section of thallus; E, cells with escaping gametes (x566). F J, con- 

 jugation of gametes (F H, x 566; I and J, x 790). K, young plant developed 

 from hypnospore ( x 566). L, Enter vmorpha intestinalis (L.) Link, from 

 Frizinghall, W. Yorkshire (nat. size). 



Genus Enteromorpha Link, 1820. The thallus is elongated, 

 tubular and intestiniform, sometimes reaching a considerable 

 length. It is green, yellowish-green, or pale olive-green in colour, 

 and consists of a single layer of rounded or polygonal cells, each 

 with a parietal chloroplast. 



The only freshwater species of the genus is E. intestinalis (L.) Link 

 (fig. 35 L), an Alga which also occurs in brackish water and in the sea. It is 

 widely distributed in the large drains and dykes in the east of England, and 

 also occurs frequently in canals and ponds in other parts of the country. 



W. A. 



