THE SPONGES OF THE WEST-CENTRAL PACIFIC 231 



mass of jelly, which is perforated by the meandering canals. There are very 

 numerous small flagellate chambers which are spherical and only 20 fi in 

 diameter. In the jelly there are scattered spicules and also a few vague tracts 

 about 50 fx in diameter. These contain about 6 to 10 spicules per cross section 

 and apparently no spongin at all. Their surface terminations are responsible 

 for the microconulose structure mentioned above. 



The skeleton is principally mesogloea or jelly, but the mineral skeleton 

 comprises oxeas about 8 ll by 620 ll. A very few of these are modified to 

 appear as strongyles, but this is here regarded as an accidental situation. 



This species may be compared to species of the genus Axinyssa, which is 

 in the same family, but is characterized by having dermal erect microxeas. It 

 might seem appropriate to name the new genus Pseudaxinyssa, because of its 

 resemblance to the older genus, but this name has already been used for a 

 genus in the Axinellidae. Several species now in other genera should be 

 referred to Pseudaxinyssa at the present time. They are as follows : Acanthella 

 ehrenbergi Keller, 1889, page 395 ; Acanthella flabelliformis, Keller, 1889, 

 page 394; Acanthella multiformis, Vosmaer, 1885, page 25; and Axinyssa 

 aculeata, Wilson, 1925, page 445. It is possible that the genus Pseudaxinyssa 

 should be further subdivided to afford a special place for those species now in 

 that genus which are set off by symmetrical, fan-like or flabellate shape. This 

 action is not taken at the present time. 



The specific name, oinops, is the Greek word meaning "wine dark" and 

 is selected because of the characteristic color of this sponge. 



FAMILY TETHYIDAE Gray 



GENUS TETHYA Lamarck 



Tethya viridis (Baer) de Laubenfels 



Text Figure No. 159 



This species is here represented by the following : 

 U.S.N.M. No. 22973, My No. M. 349, collected July 5, 1949, by diver in the 

 Pearl Pool at the west end of the lagoon at Ebon Atoll. The depth was 

 5 meters, and the substrate was dead coral. This species was quite com- 

 mon throughout the waters of Ebon lagoon. 



This sponge is almost spherical and about 2 cm in diameter. 



The exterior color in life was often black and the interior always 

 ochraceous yellow. The specimens fade to pale lavender in alcohol. The con- 

 sistency was cartilaginous. 



The surface is tuberculate with tubercles, about 1 mm high and a little 

 more than 1 mm in diameter, crowded together so that the grooves between 

 them are quite narrow. The pores were probably located in these grooves but 

 are closed in the specimen so that the oscules cannot be made out. 



