THE SPONGES OF THE WEST-CENTRAL PACIFIC 125 



Hiattrochota hiatti, new 



Text Figure No. 78 



This species is here represented by the following: 

 U.S.N.M. No. 23087, My No. M. 469, here designated as type, collected 

 August 13, 1949, by diver from Lemotol Bay in the west part of the 

 Truk lagoon. The depth was 2 meters, and the substrate was dead coral. 

 This species was extremely abundant in the vicinity of Lemotol Bay and 

 moderately abundant throughout the Truk region in general. 



The shape is briefly incrusting when young. This sponge quickly rises 

 up to a massive shape but definitely is not ramose. The vertical measurement 

 is often as much as 15 cm, the lateral dimensions as much as 20 by 30 cm. 



The exterior and interior color in life was black. The purple sol given 

 off upon handling was very much in evidence as in other species of Hiattro- 

 chota and Iotrochota. The consistency was stiffly spongy. 



The surface is exceedingly irregular. There are many lumps about 2 mm 

 high and 2 mm in diameter ; but these in turn are covered with small tubercles, 

 and there are smaller tubercles between them. The pores and oscules, being 

 closed, cannot be made out. 



The ectosome consists of a very thin protoplasmic dermis, chiefly in evi- 

 dence between the tubercles and not much over 10 /x in thickness. The en- 

 dosome is vaguely reticulate and is thickly filled with colloidal material and 

 cells. 



The skeleton consists of very abundant spicules interconnected by rather 

 small quantities of spongin. There are two distinct categories of strongyles : 

 smaller straight strongyles, 4 ^ by 245 [x, are somewhat more common at the 



-t-' 



(j £> D 0=D 



Text Figure No. 78. Spicules of Hiattrochota hiatti, X 781. A: Strongyle from the ecto- 

 some. The entire spicule is shown, but in two parts. B: Strongyle from the endosome, not 

 common. C: Style from the endosome, a common type. D: Two of the amphidiscs. 



D 



B 



