THE SPONGES OF THE WEST-CENTRAL PACIFIC 205 



B 



D — 



Text Figure No. 138. Spicules of Atergia purpurea. A: Tylostyle, X 182. B: Raphide 

 or oxea, X 182. C: Head of a tylostyle, X 782. D: Pointed termination of one of the 



oxeas, X 782. 



The ectosome is not conspicuous. There is no detachable membrane but 

 merely a somewhat denser protoplasmic structure. The endosome is exceed- 

 ingly dense and amorphous. There is a very small ratio of cavities of any 

 sort whatever. 



The skeleton consists primarily of tylostyles with elongated heads. Most 

 of these megascleres are perpendicular to the substrate, with their points 

 towards the surface of the sponge. In fact, in some places at the surface, there 

 occur what may be called dermal tufts. Deeper in the sponge, the spicules are 

 mostly in confusion. These tylostyles range from about 2 /x by 220 tt to 5 /x 

 by 410 tt in dimensions. Among them there are very numerous oxeas or 

 raphides, 1 it to 155 /a. 



There are three other species names at present in the genus Atergia. 

 Carter, 1876, page 395, described Cometella simplex from the north Atlantic 

 only very briefly, so that it cannot be said to be well known. It was an egg- 

 shaped specimen, rising on a tall stalk. Stephens, 1915, page 32, described 

 Atergia corticata, the type of the genus, from Ireland. In addition to tylostyles, 

 such as occur in purpurea, corticata had other very large ones, ramifying 

 through the sponge, 18 it by 1500 it in measurement. The oxeote spicules were 

 only 2 it by 80 it. In 1945, page 36, Dickinson described Atergia corona from 

 Lower California (Mexico). The spiculation is much like that of corticata, 

 but the cortical spicules are much smaller, so that a greater resemblance to 

 Suberites exists. 



The species name which is selected refers to the color of the species. 



GENUS AAPTOS Gray 

 Aaptos unispiculus (Carter) de Laubenfels 



Text Figure No. 139 



This species is here represented by no specimens at all. It was collected 

 in the summer of 1948 by T. E. Bullock at Eniwetok and represented by his 

 Specimen No. Z 11. 



This is a thin, incrusting sponge. 



