12 



THE SPONGES OF THE WEST-CENTRAL PACIFIC 



Text Figure No. 4. Fibers of Flippiospongia mctachromia, X 182. 



form in diameter, about 50 n, and they formed rounded small meshes, about 

 100 [i to 200 p. in diameter. As in Spongia and other Hippiospongias, these 

 fibers consist of amber spongin without inclusions. 



This is in all respects a much more obvious Hippiospongia than is Hip- 

 piospongia communis. In fact, it differs from Hippiospongia lachne only in 

 consistency and color. Lachne is a West Indian sponge of great commercial 

 value, and its fibers are extremely elastic. Those of mctachromia are, in 

 contrast, so stiff that this should not have any commercial use. The con- 

 spicuous change in color from yellow to purple was noticed long ago in 

 sponges of the genus Verongia. After many years it was reported in a 

 species of the genus ■Aplysilla. Recently a number of additional genera, in 

 various families, each proved to have one or more species characterized by 

 this peculiar transformation, which is associated both with change in pH and 

 in oxidation-reduction chemistry. Mctachromia is the only species of Hip- 

 piospongia to have this color change, which is reflected in the specific name 

 which has been selected. 



GENUS HETERONEMA, Keller 

 Heteronema eubamma, new 



Text Figure No. 5 



This species is represented by the following : 

 U.S.N.M. No. 23082, My No. M. 464, collected on August 13, 1949, while 

 wading in the west part of Truk lagoon, south of Polle Island. This 

 was near mangroves in very shallow water, less than 30 cm deep. The 

 substrate was coral sand, contaminated with mud. 



