36 



THE SPONGES OF THE WEST-CENTRAL PACIFIC 



The ectosome is a thin, fleshy dermis. The endosome is very full of 

 foreign material in the fibers and loose among the protoplasmic structures. 

 The flagellate chambers are large, sack-shaped, and coarse. 



The skeleton consists of an open reticulation of fibers about 150 /x in 

 diameter loaded with foreign debris. 



This species was first described as Spongia fragilis by Montagu, 1818, 

 page 114, and put as type of the genus Dysidea by Johnston, 1842, page 187. 

 A very extensive treatment of its distribution and synonymy will be found 

 in Burton, 1934, page 582. This is one of the very most widely distributed 

 of all sponge species. Unlike other members of the order Keratosa, its dis- 

 tribution takes it far into the Arctic and almost into the Antarctic, as well 

 as completely around the equator. It is not astonishing, therefore, to find it 

 in the Marshall Islands, but it is remarkable that the species is so uncommon 

 in this portion of the tropical Pacific. 



Dysidea avara (Schmidt) de Laubenfels 



Text Figure No. 13 



This species is here represented by the following: 



U.S.N.M. No. 22945, My No. M. 316, collected June 21, 1949, at Ailing- 

 lap-lap Atoll, by diver, at the north side of the lagoon near Matien Islet. 

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



U.S.N.M. No. 23032, My No. M. 411, collected July 30, 1949, by diver in 

 northwestern Ponape in the lagoon at a depth of 5 meters. The sub- 

 strate was dead coral. 



Oft' 



'* * *« 



VS£v:<. 





\'/?::V. : -V'?' ' 



Text Figure No. 18. Portion of the fiber of a sponge identified as Dysidea avara, X 182. 



