232 University of California Publications in Botany [Vol. 8 



The genus Microdictyon comprises species which are totally differ- 

 ent in habit from any of the other Cladophoraceae, and possesses a 

 thallus of a leaflike form and general appearance. The species may, 

 however, be considered to represent opposite branched Cladophorae 

 whose branch] ets anastomose to produce a plane, reticulate thallus, 

 the main filaments and branches giving the appearance of veins, while 

 the branchlets form the general groundwork. The species are all 

 tropical or subtropical, one species only being credited to our coast. 



Microdictyon Agardhianum Dec'ne 



Plants delicately membranaceous, filaments 50-200/^ diam., main 

 veins rather distinct, radiate, branches patent; segments usually 2-4 

 diam. long. 



Guadalupe Island, Lower California. 



Decaisne, PI. de I'Arab., 1841, p. 115. 



Collins (1909, p. 366) refers under the name Microddciyon 

 Agardhianum a plant from Guadalupe Island off the coast of Mexico. 

 Since we have not seen specimens of this, we have not attempted to 

 consider whether the Guadeloupe plant is the same as M. Agardhianum 

 Decaisne of the Red Sea or M. umbilicatum (Velley) Zanard. from 

 southwest Australia, but have left our reference under the name used 

 by Collins. 



16. Boodlea Murray and De-Toni. 



Boodlea composite (Harv.) Brand (1904, p. 187, pi. 6, f. 28-35) 

 is a tropical species, the type locality of which is the island of iMau- 

 ritius. This species has been credited to our coast (cf. Setchell and 

 Gardner, 1903, p. 226; Collins, 1909, p. 367; Yendo, 1916, p. 247; 

 Collins, Holden and Setchell, Phyc. Bor.-Amer., no. 722), An exam- 

 ination of the specimens upon which this representation is based shows, 

 however, that none of them is really the Conferva composita Harv. 

 (1834, p. 157). Collins (1918, p. 85) states that what has been said 

 concerning Boodlea composita in his Green Algae of North America 

 (1909, p. 367) is to be cancelled. Boodlea, consequently^, can not be 

 said to have been found on our coast. 



