THE SPONGES OF THE WEST-CENTRAL PACIFIC 41 



should be found to describe these surface structures. Each is about 2 mm 

 high and 3 to 4 mm apart, but the apex of each is flattened and in turn is 

 covered with minute projections. The specimen from Ebon is placed in this 

 species largely because it has this surface covered with peculiar truncated 

 cones. The pores are extremely small, only 15 /* to 35 p. in diameter. They 

 are irregularly distributed ; in places they are only 30 p, to 40 p, apart, and 

 other regions several square mm in area are devoid of them entirely. Only 

 the larger specimens show any oscules at all, and these are very small, say 

 3 to 4 mm in diameter, and readily closable. 



The ectosome is covered with a dermis that perhaps is made of spongin 

 and is about 20 p. thick. The endosome has comparatively dense protoplasmic 

 structure and relatively few fibers. In many specimens, particularly the 

 type, there are numerous bits of foreign material, such as broken shell frag- 

 ments. These shells give every indication of being in a process of solution, 

 being much eroded and softened. Where this species rested on coral, the 

 latter was also altered to a sort of white mush or porridge. The flagellate 

 chambers are sack-shaped or eurypyllous, varying from 35 p. by 75 p. to 40 p. 

 by 60 p.. In fact, a few as long as 80 p, were found. 



The skeleton of this species is not characteristic of the genus Dysldea. 

 There are fibers which at the base of the sponge start out rather large, even 

 as much as 400 p, in diameter. These may be the oldest portion of the fiber. 

 They have the dendritic shape — that is to say, they branch often. Yet, the 

 sponge is not entirely dendritic, because anastomoses do occur, making meshes 

 which in some cases are rather small but which are more often quite coarse. 

 After many branchings, near the surface of the sponge, the fibers are only 

 65 p. in diameter. 



The peculiar micro-conulose, truncated tops of the pseudo-conules doubt- 

 less result from the tendency of these fibers to branch repeatedly, especially 

 near the surface of the sponge. In places there are regions, several cubic mm 

 in area, which are completely devoid of fibers so that there is a suggestion 

 of resemblance to the genus Pleraplysilla. The new species rhax is set apart 

 rather sharply from others of the genus Dysldea by its peculiar surface, its 

 rather odd semi-dendritic skeleton, and by its distinctive combination of 

 purple ectosome and yellow or yellow-green interior. 



The species' name is selected from the Greek word for "grape" because 

 many specimens of this fruit have the greenish interior with a purple skin. 



Dysldea crawshayi de Laubenfels 



Text Figure No. 22 



This species is here represented by the following: 

 U.S.N.M. No. 22955, My No. M. 329, collected June 28, 1949, by diver at 

 Majuro Atoll in the northeastern part of the lagoon. The depth was 3 

 meters, and the substrate was dead coral. 



