64 University of California Publications in Zoology [Vol.22 



California have been consulted, however. This Staurastrum is the 

 most delicate and graceful of any ever observed by the present writer. 

 Losses through net probably very heavy. Occurrence as recorded at 

 Station I, small in numbers and scattered; May is the only month 

 yielding none. More abundant at other stations but missing in Jan- 

 uary and May. Maximum in September at all stations. This comes 

 after several weeks of strong development at Stations II and III. 

 Evidently favored by higher temperatures, 20° C. or above, but hin- 

 dered by sewage. Probably of considerable importance in summer. 



Staurastrum spp. 



Station I Station II Station III Daily Hourly 



Average 3,566 38,901 37,338 826 12,207 



Probably three or more Staurastrum are included under this head- 

 ing. There were a large number of different kinds found at various 

 times at different stations. All seem to be rather closely confined to 

 the warm season and to the water with least sewage. 



The following forms of Conjugatae were recorded only once or 

 twice or were thought to have been recognized in living material. 



Closterium gracile Breb. 



Closterium lineatum Ehrbg. Once, III. 



Closterium lunula Ehrbg. Once, II, and III. 



Closterium obtusum Breb. Once, II. 



Cosmarium botrytis Menegh. 



Cosmocladium saxonicum DeBy. 



Didymoprium sp. 



Docidium sp. 



Sphaerozosma vertebratum Ralfs. 



Spirogyra fluviatilis Hilse. Once, II. 



Spirogyra majuscula Kiitz. Once, II. 



Spondylosium depression Arch. 



Staurastrum alternans Breb. Once, III. 



Staurastrum cuspidatum Breb. 



Staurastrum eustephanum Ehrbg. Once, I and Daily. 



Staurastrum macrocercum. 



Staurastrum vestitum Ralfs. 



Xanthidium sp. 



Zygnema sp. 



CHLOROPHYLL BEARING ORGANISMS 



So few flagellates were found that were clearly non-chlorophyll 

 bearing, there was so much difficulty in separating the two types, 

 and the characteristics of the Mastigophora so clearly resembled those 



