THE SPONGES OF THE WEST-CENTRAL PACIFIC 



39 



Text Figure No. 20. Portion of the fibrous skeleton of Dysidea herbacea, X 182. 



The ectosome is quite coarse, about 400 p. thick. It contains some for- 

 eign material. It is much thicker in some places than in others and is under- 

 lain by fairly extensive subdermal canals. The endosome is typical of the 

 genus Dysidea, with flagellate chambers that are sack-shaped or eurypyllous, 

 about 35 jx to 50 /j. in measurement. 



The skeleton consists of fibers not sharply divided into primaries and 

 secondaries, although some are as thin as 40 jx in diameter and others as thick 

 as 140 fi. All are loaded with foreign debris and make a reticulation of 

 which the meshes are often triangular. 



This species was first described as Spongelia herbacea by Keller, 1889, 

 page 336, from the Red Sea. Burton in 1934, page 593, regards it as a good 

 species of Dysidea and extends its distribution throughout the Indian Ocean, 

 East Indies, and the north and south coasts of Australia, in part by referring 

 a number of other species to it in synonymy. One specimen of herbacea, as 

 noted above, was collected near Matien Islet, which was a locality from which 

 Dysidea avara was also collected. The two species were in great contrast to 

 each other. In the field, they appeared to be so different that one might 

 expect them to belong in different genera, rather than the same genus. 



Dysidea rhax, new 



Text Figure No. 21 



This species is here represented by the following : 

 U.S.N.M. No. 23013, My No. M. 393, here designated as type, collected 

 July 11, 1949, by diver at Likiep Atoll at the east end of the lagoon near 

 Lado Islet. The depth was 5 meters, and the substrate was dead coral. 



