THE SPONGES OF THE WEST-CENTRAL PACIFIC 



233 



B 



Text Figure No. 160. Spicules of Tethya diploderma, X 782. A and B: Terminations 

 of the strongyle, mid portion not shown. C: Spheraster. D: Tylaster. 



This species is spherical and about 2 cm in diameter. 



The ectosome color in life varied from yellow through orange to red. 

 The interior varied only from yellow to orange-yellow. The consistency was 

 stiff and cartilaginous. 



The surface is tuberculate, with tubercles 1 or 2 mm high and 1 or 2 mm 

 in diameter, separated from each other by only narrow grooves. The pores 

 and oscules could not be made out, because they are very readily closed. They 

 may be expected to be in the grooves between the above-mentioned tubercles. 



The ectosome is a pronounced cortex, with two distinct layers — hence the 

 specific name, diploderma. The endosome is strongly radiate. 



The skeleton consists of strongyloxeas which are definitely inequiended. 

 These range up to at least 20 ^ by 2000 p. in dimensions. The microscleres 

 include relatively large spherasters, about 60 fc to 65 /x in diameter, and also 

 include small euspherasters 15 /a in diameter. These have very numerous rays. 

 A second category of microscleres is a small euaster with tylote modifications 

 to the rays, so that it may be called a tylaster. This type is 6 fi to 10 p. in 

 diameter and has usually only from 5 to 10 rays. 



This species was first described as Tethya diploderma by Schmidt, 1870, 

 page 52, from the West Indies, but it has since been recorded from practically 

 all the warmer waters of the world so that it may fairly be called circum- 

 equatorial. 



