194 



THE SPONGES OF THE WEST-CENTRAL PACIFIC 



location. For instance, this might belong in the family Desmacidonidae instead 

 of in the family Hymeniacidonidae. In the family Desmacidonidae, however, 

 the genus which is sharply set off by having a spiculation of only strongyles 

 is Liosina, and it shows a pronounced tendency to resemble keratose sponges, 

 having a considerable amount of spongin and a tendency to grow strongly in 

 a vertical direction. 



The species name here selected obviously refers to the black color. 



Prianos osiris, new 



Text Figure No. 131 



This species is here represented by the following : 

 U.S.N.M. No. 23078, My No. M. 460, here designated as type, collected 

 August 13, 1949, by diver in the western portion of the Truk lagoon 

 south of Polle Islet near mangroves, in water discolored dark brown by 

 the vegetation. The depth was less than 2 meters, and the substrate was 

 fragments of dead coral. 



This species can be described as almost cylindrical but exceedingly lumpy 

 and irregular in outline. The mass reaches a height of 12 cm and a diameter 

 of 7 cm. 



The endosome and ectosome color in life was orange and the consistency 

 very soft. 



The surface was even but thrown into tubercles often only about 200 /x 

 high, 1 mm in diameter, and 2 mm apart. There were also the larger irregular- 

 ities which have been mentioned in the description of the shape of the species. 

 The pores are about 30 p. to 60 /x in diameter and are quite abundant in the 

 grooves between the tubercles where they may be as little as 70 /x apart, 

 center to center. The oscules are about 5 mm in diameter and 7 cm apart. 



The ectosome is detachable with some difficulty and is about 50 /x thick. 

 It is chiefly fleshy in construction. The endosome is mostly in confusion. 



The skeleton consists of: strongyles, 4 /x by 112 /x; oxeas (about equally 

 abundant), 3.5 /x by 150 /x; and smaller spicules, which are either oxeas or 

 raphides (very abundant), 1 tt by 134 /x. 



It is here suggested that the genus Prianos falls into two subdivisions, 

 which might be described as subgenera. The typical one contains cratera and 



Text Figure No. 131. 



Spicules of Prianos osiris, X 781. 

 B: Strongyle. 



A: Two of the oxeas. 



