126 



THE SPONGES OF THE WEST-CENTRAL PACIFIC 



surface than elsewhere and may be regarded as an ectosomal category, or 

 type. Larger strongyles, 13 ll by 185 ll in dimensions, are somewhat less 

 common. Most of the spicules of the interior are styles, 7.5 ii by 183 /x, and 

 very often bent rather sharply near the blunt end. The microscleres consist 

 of birotulates 14 ll in length. The clads or teeth, if any, are so small that 

 the number cannot be counted. It is almost as though the heads of these 

 spicules were saucers with even rims. 



This species, which is so characteristic of the Truk region, is set off by 

 the two types of strongyles and the rather characteristic shape of the mi- 

 crosclere. 



The specific name is given in respect to the zoologist, Dr. R. W. Hiatt. 



Hiattrochota mystile, new 



Text Figure No. 79 



This species is here represented by the following : 

 U.S.N.M. No. 23018, My No. M. 398, collected July 15, 1949, by diver at 



Likiep Atoll in the south part of the lagoon near Lukonwoerr Islet. The 



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



very common in the Likiep Atoll. 

 U.S.N.M. No. 22894, My No. M. 194, collected August 10, 1949, by diver 



in the Truk lagoon near Moen Islet. The depth was 2 meters, and the 



substrate was dead coral. 



This species is very thinly incrusting. Its vertical measurements were 

 well under 1 mm. It spreads laterally indefinitely, often covering as much 

 as 200 to 500 square cm. 



The color in life was black, and the consistency softly colloidal. When 

 one attempts to dislodge this species, one obtains latex-like strings rather 

 than any more solid material. 



The surface is extremely smooth and, of course, pores and oscules 

 cannot be made out. 



#— * 



V? 



-Dd 



B 



Text Figure No. 79. Spicules of Hiattrochota mystile. A : Strongyle from the ectosome, 



X 781. B: Style from the endosome, X 781. C: Amphidisc microsclere, X 781. 



D: Amphidisc, X 1,562 (oil immersion study). 



