54 



SIDONOPS BICOLOR. 



umbilicus usually have an elongated (Plato 11, fig. 12), those remote from the 

 umbilicus, a circular or polygonal (Plate 11, figs. 13, 14) transverse section. 

 Each ray bears a terminal verticil of from two to eight stout, conical, lateral 

 spines arising vertically from the ray. 



The young sterrasters observed in great numbers in the choanosome of 

 the specimens from Stations 3168 and 4420 were surrounded by stratified 

 capsules readily stainable with azure and apparently composed of flat enclotlielial 

 cells. The smallest of these young sterrasters was a sphere, 20 /< in diameter, 

 composed of exceedingly fine radial rays. 



DIMENSIONS OF STERRASTERS. 



LOCALITY AND NATURE OF ENVIRONMENT. 



