10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Calif.; at each place it is present in great abundance. At the type- 

 locality (Hermosa Beach, Calif.), for instance, virtually every exposed 

 surface of the rocky environment is covered with a dense mat of 

 Victorella argilla several centuneters thick. 



Turner, Ebert, and Given (in ms.) have described the ecology 

 of artificial reef environments and have recorded the impact of Victorella 

 argilla on biological succession. These authors found that hard 

 surfaces exposed to waters containing large amounts of suspended 

 sediment were colonized by V. argilla at an early stage in the succes- 

 sional pattern. The animal becomes a thick, rapidly spreading mat 

 that smothers and kills other sessile animals and inhibits the settling 

 of competitors by the dense, muddy surface it presents. At length, 

 the colony thickens, rising up into smooth knobs and clumps. These 

 thick masses break away easily and apparently the surfaces thereby 

 exposed are among the few places other animals may become 

 attached. These authors report that the colony had been noticed but 

 not recognized as organic until late in the study. It was referred 

 to as a sediment layer or a muddy mucous layer until its animal 

 nature was discovered by Given. 



The following is a list of the Polyzoa from the type-locality: 



Victorella argilla, new species abundant 



Pherusella, undescribed species present 



Tubulipora tuba Gabb and Horn, 1862 present 



Diaperoecia calif ornica (d'Orbigny, 1852) abundant 



Diaperoecia floridana Oshurn, 1940 common 



Crista occidentalis Trask, 1857 common 



Membranipora villosa Hinks, 1880 on algae 



Antropora tincta (Hastings, 1930) on Kelettia 



Scrupocellaria hertholetti Robertson, 1905 common 



Microporella calif ornica Robertson, 1908 present 



Fenestrulina malusi ('Audouin, 1826) present 



Holoporella brunnea (Hinks, 1884) present 



Distribution 



Type-locality. — California Wildlife Conservation Board, cement 

 block artificial reef, Hermosa Beach, Calif., 60 feet. Type material 

 collected by the author June 10, 1965. 



Mr. Robert Given informs me he has observed the animal at the 

 following locations: Malibu artificial reef, Malibu, Calif., 60 feet (May 

 8, 1961); Standard-Humble oil tower "Hilda," Santa Barbara, Calif., 

 from 10 to more than 110 feet (1961); artificial reef at Torrey Pines, 

 near La Jolla, Calif., 65 feet (Oct. 19, 1964); docks and piers at the 

 University of California at La Jolla; artificial reef at Imperial Beach, 

 Calif., 15-20 feet (Oct. 20, 1965); artificial reef at Huntington Beach, 

 Calif., 65 feet (Oct. 22, 1964). 



