178 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



GENUS PSEUDAXINYSSA Burton 

 Pscudaxinyssa pitys, new 



Text Figure No. 117 



This species is here represented by the following : 

 U.S.N.M. No. 23103, My No. M. 485, here designated as type, collected 

 September 1, 1949, by diver in Iwayama Bay near Koror in the Palaus. 

 It was found in muddy, discolored water near mangroves at a depth of 

 2 meters with a dead coral substrate. This species was very common 

 in this particular ecological situation. 



The shape of this species is fundamentally massive, but it is provided 

 with abundant processes, about 11 to 14 mm high and 1 to 2 mm thick, 

 situated 4 or 5 mm apart, center to center. 



The ectosome and endosome color in life was dirty drab, and the con- 

 sistency was soft. 



The surface, other than the conspicuous projections, was covered with 

 a translucent dermis over large and extensive subdermal cavities. Perhaps 

 this dermis was full of very numerous pores, but by the time the sponge 

 had reached the preserving fluid, these had all closed. The surface is pro- 

 fusely cavernous. Some or all of these openings may represent oscules ; but, 

 on the other hand, some of them may be vestibules leading only to pores. 



The ectosome structure has already been discussed and consists of the 

 conspicuous projections, the translucent dermis, and the subdermal spaces. 

 The endosome is also cavernous. Its rounded spaces are separated from 

 each other by partitions which contain spicules more or less in confusion. 



The skeleton consists principally of spicules with very little spongin. 

 These are long, sharp-pointed oxeas, about 13 p. by 800 p. in dimensions. 



The type of this genus was first described as Axinyssa tethyoides by 

 Kirkpatrick, 1903, page 245, from South Africa. This seems to have had 

 the same peculiar shape as the species pitys, but it was black in color and 

 had large spicules, 34 y, by 700 /x. The sponge first described as Axinyssa 

 gravieri by Topsent, 1906, page 563, from the Red Sea, has been referred 

 to Axinyssa, but it does not have the peculiar structure. Its spicules were 

 almost the same size as those in pitys, but it is noted as colorless in life. 

 Because of the great difference in structure, it is here considered dubious 

 that it should be referred to Pseiidaxinyssa. The third species so far placed 

 in this genus was first called Pscudaxinyssa tcnuispicula by Burton, 1931, 

 page 350, from South Africa (like the type). It was based entirely upon a 



Text Figure No. 117. Spicule (oxea) of Pseiidaxinyssa pitys, X 182. 



