110 THE SPONGES OF THE WEST-CENTRAL PACIFIC 



There are also very abundant sigmas, typical in shape and 17 ll to 18 /x in 

 chord measurement. 



This new species differs from others within the genus throughout the 

 world in numerous ways, including spicule size, but has for its closest rela- 

 tives two species described from the nearby East Indian region, which two 

 might be expected to be closely related to emphasis. Yet each of these (which 

 actually may be conspecific with one another) is characterized by extremely 

 smooth surface, whereas the present species has the very distinctive micro- 

 conulose surface. The two East Indian species here referred to were orig- 

 inally described as follows: Gellius glaberrimum Topsent, 1897, page 471, 

 and Gelliodes porosa Thiele, 1905, page 943. 



The new species receives its name from a Greek word referring to "out- 

 ward appearance." 



GENUS KALLYPILIDION, new 



This genus is here established within the family Adociidae, to have as 

 genotype the species Kallypilidion poseidon. It is characterized sharply by its 

 external shape, which is regularly that of a very thin-walled bowl or vase. It 

 is easily detached from the substratum and, when turned upside down, strik- 

 ingly resembles a brimless cap, such as a man might wear. The name is de- 

 rived from the Greek for "beautiful hat," or cap. 



Kallypilidion poseidon, new 



Text Figure No. 70 

 Plate IX, Figure a 



This species is here represented by the following : 



U.S.N.M. No. 23121, My No. M. 503, here designated as type, collected 

 September 2, 1949, by diver northwest of Koror near Ngarebagal Island 

 in the Palaus. The depth was 3 meters, and the substrate was dead coral. 



U.S.N.M. No. 22911, My No. M. 216, collected August 13, 1949, by diver 

 from the west part of Truk lagoon in Lemotol Bay. The depth was 4 

 meters, and the substrate was dead coral. This species is fairly common 

 in the Truk lagoon but even more common in the lagoons about the 

 Palaus. 



The shape is described in the generic diagnosis given above. Specimens 

 from the Truk region reached a vertical measurement of 14 cm and a diameter 

 of 11 cm. The walls at the thickest were rarely 3 or 4 mm, and the upper 

 portions of the walls were as thin as paper. Specimens from the Palaus were 

 as much as 30 cm high and 20 cm in diameter. They showed a maximum 

 wall thickness of 5 mm, but most of the wall was only about 1 or 2 mm 

 thick. 



