296 REVISION OF THK MONAXONID SPONGES,!,, 



quotes this sponge in support of his reasons for regarding ^S". 

 papulosa and *S'. cunctatrix as identical. There is good reason to 

 believe, therefore, that S. papillosa var. porosa — even though it 

 should prove to be merely a variant of >S'. papillosa — belongs to a 

 species quite distinct from any other that Vosmaer would include 

 under >S', purpurea : as we have yet no proof that it and *S'. 

 papillosa are connected by intermediate forms, and as the dis- 

 tinction between the two seems so definite, I am inclined to 

 regard it as at least an independent variety. 



Seeing that Vosmaer considers that no importance can be 

 attached to the presence or absence of papillae as an indication 

 of specific difference, I ma}^ mention that ever}^ specimen of S. 

 papillosa and of its variety I have seen, is not only provided 

 with papillae, but these always have the same characteristic ap- 

 pearance, and are always distributed over all parts of the surface 

 except in the neighbourhood of the oscula or upon the sieve-areas. 

 There may be considerable variability in the degree of develop- 

 ment of these papillae as regards their size, but scarcely any as 

 regards their relative number* ; when least pronounced, they 

 resemble those of the specimen figured by Vosmaer (PI, iii,, fig.o). 

 Besides S. papillosa, I am acquainted with at least five that I 

 believe to be quite distinct species of Spirastrella, and, in the 

 matter of papillae, no specimen of these makes any approach to 

 S. papillosa. 



The character of the papillae in S. papillosa is such as to suggest 

 that they are morphologically related to the papillae and areolae 

 of Cliona {Papillissa) lutea and its allies; because of this, I am 

 inclined to attach importance to the fact that, in many specimens, 

 both of S. papillosa and of its variety, I have found incorporated, 

 pieces of shell and other calcareous fragments which, in every 

 case, showed the characteristic perforations due to a boring 

 sponge. 



It remains to be mentioned that, in connection with the two 

 figures given in the "Catalogue"(Pl. i., figs. 1-2), which purport to 

 be in illustration of Papillina panis, a serious mistake has been 

 made : the first is unmistakably a figure of Cliona {Papillissa) 

 lutea, and the second is one of Spirastrella(i) ramulosa. 



