THE SPONGES OF THE WEST-CENTRAL PACIFIC \\ 



differs only slightly from the typical variety as found in the Mediterranean 

 region, described as Spongia communis by Lamarck, 1814, page 370. Because 

 it is a potentially valuable commercial form, and therefore likely to be 

 referred to frequently in such a manner as to require differentiation from 

 the Mediterranean form, it seems advisable to give it a name at this time. 

 The basis for separation is admittedly a small one. In the Pacific form there 

 are exceptionally conspicuous ridges between the conules, forming a note- 

 worthy stellate pattern on the surface. 



The subspecific name is derived from the native name for this organism. 



Hippiospongia metachromia new 



Text Figure No. 4 



This species is represented here by the following : 

 U.S.N.M. No. 23123, My No. M. 505, here designated as type, collected on 



September 2, 1949, by diver in the Palaus northwest of Koror in the 



lagoon near Ngarebgal Islet. The depth was 3 meters, and the substrate 



was dead coral. 



This species appears to be rare ; only the one specimen was found. 



This is a massive sponge, 14 cm high and 22 by 30 cm in horizontal 

 measurement. 



In life the exterior was brilliant yellow, and the endosome would have 

 been the same color, except for the modification thereof by an obviously 

 abundant reticulation of amber-colored fibers. After dying, either in the air 

 or in alcohol, the sponge very slowly turns dark purple. It required 5 min- 

 utes to see any obvious change, and 5 hours for the maximum change. The 

 odor in life was that of the characteristic West Indian Spongia and Hippio- 

 spongia. The consistency was stiffly spongy. 



The surface is typical for the genus Hippiospongia. There is an obvi- 

 ous fleshy dermis, about 20 /i thick over large, extensive subdermal cavities. 

 In the islands between these ramifying cavities or canals, the surface is cov- 

 ered with sharp conules about 3 mm high and 6 mm apart. The pores are 

 microscopic and close quickly. The oscules are difficult to study, because the 

 specimen contained a large number of openings which are probably accidental. 

 Yet, some must be oscules. Probably none are much more than 1 cm in 

 diameter. All are irregular in outline and inconspicuous. 



The ectosome (as already mentioned) is a sharply differentiated dermis 

 closely adherent to the underlying tissues and removable only with great 

 difficulty (which is characteristic for the genus). The endosome is densely 

 crowded with spherical flagellate chambers, 25 p. to 30 ^ in diameter, and is 

 full of a fibrous reticulation. 



No ascending or cored fibers could be located at all ; the only type present 

 is that which is sometimes termed secondary. These fibers were rather uni- 



