REPORT ON THE HEXACTINELLIDA. 285 



predominate, and indeed the anchor-like forms may decline to such an extent, that they 

 are only found here and there. 



I have taken special pains to try to elucidate the characters of the soft body and 

 especially the system of chambers in those specimens which are best preserved. Neither 

 the dermal nor the gastral membrane exhibits any special peculiarities. Where the 

 dermal network has been in any way preserved, it exhibits meshes of variable width, 

 sometimes very narrow as represented in PI. LXXI. fig. 3 and PI. LXXII. fig. 5, 

 and sometimes so wide, that the whole rectangular region between four adjacent 

 pentacts exhibits only one large round aperture. The gastral membrane exhibits similar 

 relations. 



In the younger portions, which are supported only by a single reticulate layer of the 

 dictyonal framework, the chambers form a simple, or slightly folded layer of large sac- 

 cular or thimble-shaped diverticula of variable size. Below the rectangular meshes of the 

 dictyonal framework, they unite to form a wide excurrent space (PI. LXXI. fig. 3), so 

 that, on looking down from the gastral surface, below each mesh, one finds a large 

 excurrent aperture. When the thickening of the wall towards the base of the stock 

 results in a dictyonal framework of several layers, broad canals traverse this thick wall. 

 The chambers, which are directed obliquely, then appear rather as lateral and terminal 

 diverticula of the wide principal canals, and seem to be continuous with them without 

 any marked boundary (PL LXXIII. fig. 2). 



The number of chamber-wall pores varies greatly in the different regions of the body 

 and in different specimens. The thin layer of connective substance which forms the walls 

 of the chambers bears internally the epithelial cells, arranged in rectangular fashion as in 

 Euplectelta, and also united by the same lateral processes into a rectangular network. 

 The trabecular framework which extends between the two bounding membranes and 

 the chamber layer consists of delicate strands with fine expansions at the points of 

 insertion and union. 



In many cases the external surface of the chamber wall exhibits numerous groups of 

 small, crowded cells, with nuclei which stain with special readiness. It is possible that 

 these groups of six to twelve cells are concerned with reproduction ; I have at least 

 remarked their total absence in several specimens which contained numerous sperm balls 

 at various stages. I have unfortunately found no ova or larvae. It is true indeed that 

 in one fragment from Sagami Bay, the subdermal trabecular space contained numerous 

 blastulfe in some regions, but whether these belong to the Farrea or to some 

 commensal, or perhaps to some quite unconnected form, it is difficult to determine, since 

 the state of preservation of the specimen was by no means favourable. The minuteness 

 of the larvse (0'03 mm. in diameter) seemed, however, noteworthy. 



__l 



