1920] Setchell-Gardner : Chlorophyceae 211 



sive distribution is to be explained, in all probability, by its occurrence 

 so high up in the littoral belt that it is enabled to receive much heat 

 from the sun and the air, while its dense tufts allow it to remain 

 exposed at low tide without drying. 



Cladophora trichotoma f. elongata Collins 



A luxuriant form, sometimes up to 3 dm. high ; fronds sparingly 

 branched except near the surface of the water, where it forms char- 

 acteristic dense tufts. 



Growing on the margins of deep rock pools little affected by tides. 

 Point Carmel, "Point Lobos," Monterey County, California. 



Collins, i)i Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 2141, Green Alg. Suppl. II., 1918, p. 81. 



The typical form of Cladophora trichotomy is truly a member of 

 the Aegagropila section of the genus Cladophora and occurs in dense 

 cushions or tufts, low and spreading by prostrate branches which 

 descend, attach themselves, and send off erect branches in turn. When 

 growing in deep rock pools, and, therefore constantly immersed, the 

 low cushions give off erect and luxuriant tufts of filaments, loosely 

 entangled and sparing branched, until thej^ reach the surface. These 

 erect tufts simulate the plants of the Eucladophora section, and may 

 pass for them unless care is taken to study the base. We feel fairly 

 certain in referring here no. 127, Butler and Policy, collected at Port 

 Renfrew, British Columbia and listed in Setchell and Gardner, Algae 

 of Northwestern America (1903, p. 228) as Cladophora Hutchinsiae 

 var. distant. 



4. Cladophora graminea Collins 



Plants loosely tufted, 10-15, cm. high, dark green, cartilagineous, 

 very rigid, distantly di-trichotomous, all divisions erect; main fila- 

 ments about 300/x diam., ultimate divisions about 150/x diam., tips 

 blunt or slightly acute; segments very long below, up to 30 diam., 

 shorter above, normally occupying the space from one forking to 

 another; ultimate branches 4-6 diam. long; segment walls usually 

 strongly lamellate. 



Growing in rock pools usually in shaded habitats, in the upper 

 littoral belt. Known along the California coast from Monterey to 

 San Diego. 



