146 I. IJIMA : HEXACTINELLIDA. I. 



soon after its origin from the nuclear surftice, and to pursue its 

 course edgewise, either for a part or the whole of the remainder 

 of its passage through the structure in question. This fact 

 indicates that the latter structure must he hollow from its hase. 

 4) Tlie collnm-like section may be only a ])orHon of tlir collar. 

 Significant in tliis respect appear the flattened cake-like form of 

 the basally situated nucleus, notwithstanding the elongate shape 

 assigned to the cell-body. It is also to be noted that the collum- 

 like section should have, according to the describer, clear contents, 

 the granules being apparently confined to the region immediately 

 around the nucleus and to the reticular bands in the membranous 

 basal expansion, — a fact which strikes me as somewhat remarkable. 

 And, I venture to say that some of Schulze's figures — notably 19'ff, 

 Taf. Ill, Fig. 4, which shows no material difference in appear- 

 ance between the collar and the collum, while the angular lateral 

 edge-line between the two parts may be taken as due simply to the 

 presence of the peculiar connecting membrane at that level — 

 are in no small measure suited to give an impression pointing 

 to the possibility, not to say the probability, of the present 

 assumption. However, it will require more substantial grounds 

 to establish the point. After all, 1 am inclined to give weight 

 only to the first and the last of the four above-mentioned possi- 

 bilities in the way of explaining the position I have taken as 

 regards the structure of the choanocyte in E. marshalli. 



Fourthly, an interesting discovery was made by Schulze in 

 S. arctica in that the closely standing distal ends of the collum- 

 like section of the choanocytes, at the boundary between them 

 and the collar, were connected laterally with one another by a 

 cementing mass, though at times they appeared there to be 

 simply sticking together. In the plate-like connecting mass sur- 



