22 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.81 



Station 2925, near San Diego, Calif., latitude 32° 32' N., longitude 117"* 



24' W., depth 620 meters, mud bottom. 

 Station 2935, near San Diego, Calif., latitude 33° 04' N., longitude 117" 



42' W., depth 839 meters, mud bottom. 



In the dredging operations of E. F. Ricketts, of the Pacific Bio- 

 logical Laboratories, Pacific Grove, Calif,, there have been brought 

 up and presented to me by him, macerated skeletons evidently 

 belonging to the genus AphrocalUstes and very probably to the 

 species vastus; but they lack the soft parts and loose spicules. 



Order MYXOSPONGIDA SoUas 



Family HALISARCIDAE Schmidt 

 Genus HALISARCA Johnston 



HALISARCA SACRA de Laubenfels 



Halisarca sacra de Laubenfels, 1980, p. 25. 



Holotype.—U.S.'NM. No. 21454; B.M. No. 29.8.22.53. 



Type locality. — Elkhorn Slough, at the east side of Monterey Bay, 

 Calif. Collected by E. F. Ricketts, July 4, 1929. I also have col- 

 lected the species at the same locality. It is found associated with 

 MycaJe niacglnitiei on rocks introduced by man in the midst of an 

 environment of sheltered tidal mud flats. 



Description. — Shape, encrusting. Size, up to 0.7 mm thick, in 

 patches up to 14 mm in diameter. Consistency, very soft. Color 

 in life and when preserved, very pale drab. Oscules, about lOO/x, to 

 200/* in diameter. Pores, very minute, well under 50/*; exact sizes 

 obscured by contractility, but none observed more than lOyn. Sur- 

 face, superficially shiny smooth. 



Ectosomal specialization, 20/* to 40/li thick, characterized by 

 rounded cells in a more darkly staining ground mass than that of 

 the endosome. There are subdermal cavities about 20/i in diameter, 

 Endosomal structure, coUenchymatous. The abundant mesogloea- 

 takes nuclear stains very definitely. Histological details : The ex- 

 ceedingly long flagellate chambers are often radiately clustered around 

 excurrent canals, which are often near the substrate. Many proso- 

 pyles are very short, and often there is almost direct contact with 

 the subdermal cavities. The chambers are always about 40/u, in 

 diameter, and average well over 200/i, long, lengths up to 280/* being 

 common. 



Remarks. — Some authors regard all Halisarcas as conspecific with 

 H. dujardini, the genotype. The genus is so simplified that it is 

 very difficult to find adequate grounds for separating any species 

 from dujardini, but I hesitate to believe that all the members found 

 over the entire world really are conspecific. This, our California 



