THE SPONGES OF THE WEST-CENTRAL PACIFIC 189 



This species occurs in vaguely laminate or lobate, almost amorphous 

 masses, usually taller than wide. The height is often 6 to 8 cm, and the 

 diameters under 6 cm. 



The color in life of my specimens was orange, that of Morrison's speci- 

 mens is not known. The consistency was mediocre, easily torn. 



The surface is somewhat uneven in some places and smooth, almost con- 

 ulose elsewhere. The specimens appear to be lipostomous. 



The ectosome is a fleshy dermis, detachable only with difficulty and in 

 small bits. The endosome is chiefly in confusion, but vague tracts can be 

 found, 70 [x to 200 /x in diameter, branching and reuniting at acute angles. 



The skeleton comprises numerous spicules of great variation in size. 

 These are nearly always styles, but some show faint indications of elongate 

 heads, almost as in tylostyles. The sizes range from at least as small as 0.5 /x 

 by 80 ii up to at least 4 [x by 170 /x or 3 fx by 260 /x. 



The relationship between Hymeniacidon and Stylotella still awaits more 

 evidence and study. My first impression was that the Ebon specimen was a 

 juvenile Stylotella agminata, but it and the many Bikini specimens clearly 

 conform to the definition of Hymeniacidon. They are not at all close in 

 resemblance to most immature sponges of the family Suberitidae, whereas 

 Stylotella is regarded as being in this family. Old Suberitids commonly show 

 the characteristics which Stylotella possesses, especially the coarse, woody 

 fibers. Thus, one would expect juvenile Stylotella to resemble other immature 

 Suberitids and not the specimens which are now being considered. In the 

 Carolines I found many small Stylotellas which were obviously immature, and 

 they were very different from aldis and dystacta. 



Hymeniacidon dystacta is more like species of this genus from Europe, 

 such as H. caruncula, than like others which have been described from the 

 Pacific. The latter have spicules far larger than those of dystacta, and there- 

 fore are (in this respect) more like Stylotella than is dystacta. On the other 

 hand, caruncula' s spicules are much shorter than those of dystacta. 



The species name selected is taken from the Greek, meaning "difficult to 

 classify." 



GENUS NEOPROSYPA, new 



This genus is here established in the family Hymeniacidonidae, to have 

 as type the new species Neoprosypa atina. It may be defined as having a 

 spiculation of oxeas and styles accompanied by trichodragmas— with the 

 further remarkable circumstance that all or nearly all of the megascleres are 

 completely acanthose. This, therefore, reads on paper as though the genus 

 should be placed in the family Acarniidae of the Poecilosclerina. On the other 

 hand, the spicules of the members of this latter family are coarsely spined, 

 whereas the species atina has only very fine spines on the spicules. But for 



