32 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



cases, are so densely filled with coarse foreign material that their outlines are 

 extremely lumpy. There are even more common secondary fibers present, 

 usually about 80 {x in diameter but varying from 50 fi to upward of 100 \x. 

 These show pale white or yellowish white spongin in concentric layers or lam- 

 inae and almost always contain a linear core of debris. Here and there an 

 occasional bit may be found to lack all foreign material, but one could scarcely 

 say that the sponge was characterized by secondary fibers clear and free of 

 foreign debris. 



Until recently there existed in the literature only one species of the genus 

 Thorectopsamma, and furthermore only one specimen of that. This was 

 recorded by Burton, 1934, page 577, for a sponge dredged from a depth of 

 45 meters, near the northern portion of Australia and named Thorectop- 

 samma irregularis but, unfortunately, not illustrated. In view of this great 

 rarity of the genus in all other portions of the world, its extreme abundance 

 throughout the Marshalls, the Carolines, and Palaus is noteworthy. 



In 1950, page 20, de Laubenfels described a small peculiar "bleeding" 

 species from Bermuda as Thorectopsamma chromogenia. 



As compared to mela, irregularis was an irregularly massive, lipostomous 

 sponge. Burton says that it has no dermal skeleton. He gives no data re- 

 garding its flagellate chambers. 



It was originally intended to name this species melanodactyla, from the 

 Greek words for "black" and "fingers." The genus name, however, is so 

 very long that it seems inappropriate to have also an extremely lengthy species 

 name. Therefore, the abbreviation mela is selected. 



Thorectopsamma xana, new 



Text Figure No. 16 



This species is here represented by the following : 



U.S.N.M. No. 23000, My No. M. 379, here designated as type, collected July 

 11, 1949, by diver at Likiep Atoll in the southeast corner of the lagoon 

 near the church. The depth was 3 meters, and the substrate was dead 

 coral. 



U.S.N.M. No. 22948, My No. M. 321, collected June 24, 1949, by diver at 

 Ailing-lap-lap Atoll in the east end of the lagoon near Jih Islet. The 

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



U.S.N.M. No. 22828, My No. M. 103, collected June 11, 1949, by hand 

 while wading at Ailing-lap-lap Atoll in the south side of the lagoon, 

 Bikajela Islet. The depth was at low tide, and the substrate was dead 

 coral. 



U.S.N.M. No. 22954, My No. M. 328, collected June 28, 1949, by diver at 

 Majuro Atoll at the east end of the lagoon near Rita or Jarej Islet. The 

 depth was 4 meters, and the substrate was dead coral. 



