THE SPONGES OF THE WEST-CENTRAL PACTFIC 83 



different : the pores of this sponge from Koror are 500 fi in diameter and 1 

 to 2 mm apart. The other specimen here discussed from Koror (No. M. 504) 

 is very much like the type, but its exterior was chocolate brown and its 

 interior peach color. Its spicules were also different, many of them reaching 

 the dimensions of 6 /x by 120 fx. Since the type specimen is from Ponape, 

 it is curious to note that others from that same island differed strikingly. 

 No. M. 403 had the typical color of the interior, but its exterior colors were 

 remarkable indeed. The upper surface was ochre yellow; the lateral surfaces 

 were blue or violet, blending into each other; but the lower surface was pale 

 drab like the interior. Of course, the dark subdermal layer was present. This 

 specimen also differed markedly in spiculation ; its megascleres were 8 /x by 

 460 p. A third specimen from Ponape differed in another respect, perhaps 

 fully as strikingly. This one, No. M. 410, otherwise very much like the type, 

 had spicules which were acanthose in about the middle sixth of their length. 

 These spicules appeared at first to be centrotylote but, upon careful observa- 

 tion, the swelling proved to be a mass of spines aggregated closely together 

 rather than a tylote swelling. 



It would obviously be possible, perhaps advisable and correct, to regard 

 these above described specimens as representing a minimum of six species. 

 It seems clear that the specimens of the genus Neopetrosia urgently want 

 further study. All those described are here put into the one species pandora, 

 because of the fact that each one is much like the type specimen in all except 

 one or two characteristics and because the most striking differences occurred, 

 not as between those from different localities but amongst specimens growing 

 almost side by side. 



Certain characteristics seem to be consistent and dependable for all the 

 specimens of that which is here regarded as the one species pandora. One 

 may note especially the conspicuous subdermal black or blackish layer, about 

 500 /x below the surface and 500 fi thick. All these specimens have the same 

 general appearance of surface and the same consistency and feeling to the 

 fingers. The oscules are very similar. When carefully examined, many or 

 all the oscules may be found to possess a sphincter, or rather a membrane, 

 which may be pulled across them. In some cases this membrane closed as 

 quickly as within five minutes after removal from the water. 



In the West Indian region there is a species, Neopetrosia longleyi de 

 Laubenfels, 1932, page 54, which is widespread and abundant. I have studied 

 literally hundreds of specimens of it from various localities, and have used 

 it for physiologic experimentation. It shows amazingly little variation; its 

 specimens are monotonously similar. Its spicules are about 3 p. by 120 /x. 

 Its color falls within the range of variation shown by pandora, but the two 

 are not here regarded as conspecific. 



Ridley and Dendy, 1886, page 327, described a sponge as Petrosia 

 similis from the southern portion of the Indian Ocean. Wilson, 1925, page 



