THE SPONGES OF THE WEST-CENTRAL PACIFIC 



259 



triradiates." Tanita used the genus Lcucandra, which falls in synonymy to 

 Leuconia. I was unable to find any similar sponges in my extensive survey of 

 the Palau region, but it may be that Tanita and his assistants had access to 

 other regions than those which I visited in the summer of 1949. 



Leuconia palaoensis (Tanita) de Laubenfels 



Text Figure No. 182 



This species is not represented by any specimen in the present collection. 

 It is recorded only by Senji Tanita, and there was no collection data other 

 than "from Palau in the Caroline Islands." It would be most interesting to 

 know the precise ecological placement of these Leuconias. 



This species is described as being a branching colony, the individuals a 

 little over 1 cm in diameter and a little over 2 cm high. 



The color in alcohol is described as rusty yellow and the consistency as 

 firm. 



The surface is smooth, the pores not described, but the oscules are said 

 to be about 2 by 4 mm. 



The ectosome is very thin, and the endosome exhibits a typical rhagon 

 structure with flagellate chambers, 80 p. to 130 ju. in dimensions. 



The skeleton comprises a number of triaxon and tetraxon spicules. Those 

 which are tangental to the interior surface have rays about 30 ti by 380 /x. 

 The ones of the chamber layer, called tubar triradiates by Tanita, have re- 

 markably large rays, 80 /x by 400 /x. There are sagittal triradiates, with their 

 clads in the lining of the cloaca and their rhabd perpendicular to the cloaca, 

 piercing the chamber layer. These have rays about 40 p by 500 ti. The spicules 

 which lie tangental to the cloacal surface are triaxons with rays 17 fx by 240 tt 



Text Figure No. 182. Spicules of Leuconia palaoensis, X 60, after Tanita. A: Cloacal 

 triact. B: Tubar triact. C : Cloacal tetract. D: Subcloacal triact. E: Triact from the 



oscular margin. 



