CRATEROMORPHA MEYER! RUGOSA. 73 



This stalk expands somewhat abruptly at its upper end ; it 

 is more or less distinctly compressed laterally. In the specimen 

 of fig. IT), the major transverse axis of the body measures 

 172 mm., the minor falling short of it by nearly 50 mm. The 

 wall, which is thin along the oscular edge, shows a considerable 

 thickness below. The osculum is large and wide, being of an 

 oblong shape though quite irregular in outline. The irregulari- 

 ties of the external surface, which form the most conspicuous 

 feature of the subspecies, are apparently due : firstly, to the thicken- 

 ing out of the wall into protuberances similar to those of tubero- 

 sa, these being generally most prominent in the lower part of 

 the l^ody ; and secondly, to the tact that the general surface is 

 thrown into low and sharp-edged wrinkles, such as arise on cer- 

 tain soft substances when they become parched. In the sponges 

 before us there can be no doubt whatever that the rugosity is 

 something natural to them and not a postmortem feature. 



Except in the above character, the texture and general ap- 

 pearance of the sponge are in essential agreement with typi- 

 cal C. meyeri but especially with the subs2)ecies ivherom. I may 

 specially mention that as regards the appearance of hypodermal 

 strands and of the gastral surface (see fig. lö), what I have said 

 under tuberosa is equally applicable here. 



The agreement extends to the spiculation also. But there 

 exists one, probably not unimportant point of difference in the 

 fact that in no specimen of rugosa have I found hexactins among 

 the parenchymalia, these consisting exclusively of diactins. This 

 negative result was reached in spite of a special search made in 

 a number of preparations. 



Exactly as in tyberosa, the hypodermalia in the body pro- 

 per are mainly diactins ; pentactins occur only here and there 



