THE SPONGES OF THE WEST-CENTRAL PACIFIC 49 



This sponge is conulose with conules 3 mm high and 5 mm apart, each 

 conule representing the upward termination of a skeletal element. There 

 are skeletal pores which are about 280 /j. in diameter, filled in with a very- 

 thin membrane, which is perforated by smaller pores. The latter are only 

 some 10 ft to 30 ,ti in diameter. Typically, there are about 25 such within 

 each large pore. No difference can be made between exhalant and inhalant 

 openings. 



The ectosome and endosome are loaded with foreign debris. Much of 

 this foreign material consists of broken spicules of various sorts from other 

 sponges occurring in the vicinity. 



The skeleton consists of widely separated dendritic fibers about 90 /x in 

 diameter. These branch only a few times before they reach the surface of 

 the sponge and there account for the conules. 



This species was described as Aplysilla polyraphis by de Laubenfels, 

 1930, page 29, and in 1932, page 126, from the coast of California. The 

 agreement between the previous specimens and this from Ponape is aston- 

 ishingly great. It seems quite strange to think of the same species occurring 

 in the western Pacific and in the cold waters off California. On the other 

 hand, various species of Aplysilla, especially A. glacialis, are known to be 

 practically cosmopolitan in distribution. It may be that this species is equally 

 widespread but more rare, and therefore seldom discovered. 



FAMILY HALISARCIDAE Vosmaer 



GENUS HALISARCA Dujardin 



Halisarca metabola, new 



Text Figure No. 28 



This species is here represented by the following : 

 U.S.N.M. No 22962, My No. M. 336, here designated as type, collected 

 June 29, 1949, by diver at the west end of the lagoon, Majuro Atoll, in 

 the miniature lagoon near Laura Islet. The depth was 2 meters, and 

 the substrate was dead coral. Several other specimens of the same sort 

 were observed in this limited vicinity. 



This is an incrusting sponge, occasionally reaching a thickness of 2 mm 

 and aggregating about 20 square cm in total area. 



The endosome and ectosome color in life was a beautiful yellowish 

 green. Upon dying either in the air or alcohol, it turned quickly to an 

 opaque blackish green and finally to very black. The consistency in life was 

 a colloidal sol, about like that of raw egg-white. In alcohol the sponge shrinks 

 in size and has become much tougher. 



The surface of this species is glistening shiny smooth. The pores and 

 oscules are indistinguishable, microscopic, and quickly closed. 



