THE SPONGES OF THE WEST-CENTRAL PACIFIC 



247 



The ectosome is a thin fleshy dermis, and the whole endosome is, as 

 characteristic of the genus, very densely fleshy with the general appearance 

 and somewhat the feeling of meat. 



The skeleton is quite typical of the genus and species. It consists al- 

 together of spicules which probably are either actually triaxons, or reduced 

 triaxons. Some of these are quite regular with rays about 1.5 /a by 25 /x. 

 Others have rays which are bent at very distinct angles with two or three 

 bends per ray. These rays are often as large as 2 [x by 30 fi. Another type of 

 spicule which is very common appears to be two such bent rays with the 

 third one very short or suppressed. The effect is at first like that of an exceed- 

 ingly crooked oxea, but it is dubious if any genuine oxeas are present in this 

 species. 



This species was first described by Schulze, 1880, page 430, from the 

 Mediterranean region. It has since been recorded by many authors in places 

 quite around the world and may be described as a circumequatorial sponge. 



Plakortis lita, new 



Text Figure No. 171 



This species is here represented by the following : 

 U.S.N.M. No. 23069, My No. M. 449, here designated as type, collected 



August 10, 1949, by diver near Moen Islet in Truk Lagoon. The depth 



was 3 meters, and the substrate was dead coral. 

 U.S.N.M. No. 23033, My No. M. 412, collected July 30, 1949, by diver in 



northwest Ponape between the reef and shore. The depth was 5 meters, 



and the substrate was dead coral. 

 U.S.N.M. No. 23045, My No. M. 424, collected August 1, 1949, by diver in 



eastern Ponape (Matalanim) from a reef in the lagoon near an entrance 



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



This is not a common species. 



The species is semi-incrusting, from 1 to 2 cm thick and often as much 

 as 18 cm in lateral dimension. 



Text Figure No. 171. Spicules of Plakortis lita. A: Larger spicules, X 782. B: Smaller 



spicule, X 782. C : Much bent, dubiously spiral microscleres, X 782. D: Typical mega- 



sclere, X 1,564 (oil immersion). E: Microscleres, X 1,564 (oil immersion). 



