RITABDOCALYPTÜS CAPILLATFS. 280 



made up of a cobweb of filamentous trabeeula' iiiteriiallv as well 

 as ill tlie most superficial situation, similar to the trabecular cones 

 on the dermal surface of Euplectella marshalU (Contrib. I., p. 

 123). Sometimes the trabecular substance may extend as a thin 

 film vertically between adjacent proxini;il rays of gastralia in a 

 sail-like manner ; at other times I have seen it in the form of 

 thin isolated threads running straight from one cone to another 

 or directly between the terminal parts of the rays, each of which 

 basally supported a cone. Such being the real circumstances, the 

 term gastral membrane, unless used with certain explicit reserva- 

 tions, would be apt to lead one into misconceptions. 



Thesocytes occur in aVuindance. I have seen them mostly 

 in the dermal layer and on trabecuhie of the subdermal s})ace. 

 Numbers of them may l)e recognized in figs. 18 and 19 as spherical 

 or ovoid and often conglomerate-like ])odies which are stained as 

 well as trabecular nuclei but are much larger. Several are shown 

 much more highly magnified in fig. 21. The cells are of various 

 sizes, from 4// up to 15/^ in diameter. The small nucleus is 

 generally seen pressed against the cell-surface, where there probaldy 

 always exists a delicate envelof)ing membrane. In the smaller of 

 the cells the contents may sometimes appear to be simply finely 

 granular or homogeneous ; otherwise they are seen to contain, or 

 rather to consist of, one or more fat-like spheres of the same 

 microchemical character as the thesocytal contents of other Hex- 

 actinellids. Of the larger thesocytes the majority are represented 

 by compact conglomerate-like groups of the same spheres, showing 

 the appressed nucleus at some part of the periphery. The not 

 very numerous spheres in one such cell are comparatively large 

 and may give it a rosette-like appearance. Thesocytes of the 

 above description I consider to be such as have attained full 



