from the. South Coast of Devon. 9 



figure 35. Nor is there any spicular combination given by 

 Schmidt like it. 



It is frequently overgrown by other sponges, especially 

 Halichondria panicea and //. simulans, Johnston. And in 

 one specimen which I possess, where it has been overgrown 

 by SL Microciona (Bk.), the areolar structures of the two sponges 

 have grown so much into each other, that a section represents 

 the same condition between the two as that which would be 

 seen in making a section of the union between a shoot of one 

 tree and another on which it is grafted. 



When preserved in spirit, this sponge assumes a lead- 

 colour — and when dried, a very light brown or dirty white. 

 In the latter state it is much less compact than Dercitus niger^ 

 owing to the more open condition of its areolar structure and 

 the larger size of the excretory canals, which are therefore 

 much more evident than in the more compact structures. 



How far the horizontal position of the spicules may be 

 owing to its shore habitat, where it is exposed to the beating 

 influence of the waves, I am not prepared to say ; nor can this 

 be determined until a* specimen of the same sponge is obtained 

 from a deep-sea habitat, if any exist there, where it would be 

 more at rest during development. 



Nitric acid applied to the cell of the celluliferous layer, here 

 as well as in Dercitus niger^ causes the whole to contract 

 slightly, and breaks down the cellules, but does not alter much 

 the large nuclear (?) or small nucleolar (?) bodies. 



Liquor potassse causes the whole to expand, breaks down 

 the cellules, and allows them to run together in the form of 

 several globular masses of oleaginous or albuminous-looking 

 matter. 



Iodine breaks down the cellules, but does not render the 

 nuclear and nucleolar bodies more evident. 



Thus these agents do no more than render the nuclear 

 and nucleolar bodies more evident by breaking down the cel- 

 lules. Perhaps, too, the nucleolus under nitric acid becomes 

 a little more consistent or opaque. 



Stelletta lactea, milii, PI. IV. fig. 15. 



Massive, spreading, fixed, following and filling the cavities 

 of deciduous small boring shells [Saxicavce] and Annelids, 

 which confine themselves to the surface of the sandstone rock 

 in which they live, almost entirely concealed by overgrowtlis 

 of small Cirripedes and Fuci, and communicating with the 

 exterior only through the openings of the cavities mentioned. 

 Dermal layer (figs. 15 Z>, 16 h) thin, white, densely charged with 



