228 I. IJIMA : HEXACTINELLIDA. I. 



the entire body-length. So that, after death and the washing 

 away of all the loose spicules, only the inferior portion of the 

 sponge remains with any degree of persistence as a perforated 

 but compact cup with a solid knobby base. In this condition 

 are several specimens now before me. Fortunately, all these, 

 dead stumps as some of them are, still contain the spicules charac- 

 teristic of the species, which puts the identification beyond the 

 reach of doubt. 



PI. VII, fig. 4 represents, in natural size, the macerated 

 remnant of the skeleton of a comparatively small and young 

 specimen. It consists for the most part of fused spicules. I 

 may remark that the general appearance of this specimen strongly 

 reminds me of one of the two specimens on which O. Schmidt ('8o, 

 p. 4G ; Taf. Vir, 3 a) based his Rhahdodictyuiii delicatum. 



PL VII, fig. 3 shows in a typical way the dead skeleton of 

 a large specimen. The wall exhibits externally an irregular 

 network of hard and more or less prominent ridges. It scarcely 

 needs to be mentioned that these arose by the soldering together 

 of parenchymal bundles in the parietal ledges. In the depressed 

 spaces bounded by the ridges are situated single, less frequently 

 several, roundish gaps, indicating the position of parietal oscula 

 in the living state. Immediately around the gap, the wall forms 

 a netted plate made up of a number of spicular strands branching 

 oil* from neighboring coarser bundles and running tangentially 

 in all directions. The coarser bundles, some of which may be 

 nearly 1 mm. thick, are seen to run in the main in two opposite- 

 ly directed, oblique sets. In their course they iTcely split, unite 

 and intersect or pass through one another, thus giving rise to 

 an irregular basket-work which may, on that account, be readily 

 distinguished from the more regularly framed skeleton of Uic- 



