THE SPONGES OF THE WEST-CENTRAL PACIFIC 



217 



The ectosome and endosome are not distinct, and the structures are 

 chiefly in confused arrangement. 



The skeleton consists of tylostyles with extremely well developed heads. 

 The necks are often so small that the heads become broken off when the 

 spicules are being prepared for microscopic observation. The larger spicules 

 are often about 12 (i by 240 [x, with heads 15 jx in diameter. Smaller (perhaps 

 juvenile) spicules are often 5 ^ by 220 /x, with heads 8 ^ in diameter and 

 necks only 2 /x in diameter. These heads were found to be covered with small 

 (one n) tubercles in many of the megascleres of the specimens from Truk 

 and from Rongerik. The microscleres are thin, undulatory spirasters, 27 fx 

 to 40 ix long, often with 4 waves or spirals. The shaft is about 0.3 fx in 

 diameter and is covered with very fine, very sharp spines. No microscleres 

 were found in specimens M. 376, N. 021, and N. 028. In all species of Cliona 

 it often happens that microscleres are absent from some portions of the 

 sponge while present in others. 



Cliona lobata was first described by Hancock in 1849, page 341, from 

 the North Atlantic region. It appears to be moderately common on both sides 

 of that ocean. Burton, 1935, page 78, records it from Japan. Doubtless care- 

 ful search would reveal its even more widespread occurrence. 



Cliona schmidtii (Ridley) Topsent 



Text Figure No. 148 



This species is here represented by the following : 

 U.S.N.M. No. 23117, My No. M. 499, collected September 2, 1949, by divers 

 northwest of Koror in Komebail Lagoon of the Palaus. The depth was 5 

 meters, and the substrate was dead coral. 



Text Figure No. 148. Spicules of Cliona schmidtii, X 782. A: Medium-sized tylostyle; 

 the entire spicule shows, but in two parts. B: Head of one of the larger tylostyles. 

 C: Head of one of the smaller tylostyles. D: Thicker type of spiraster. E: Thinner 



type of spiraster. 



