CRATEROMORPHA CORRUGATA, 81 



tares, mostlv under 2 mm. in diameter. Lower down, larger 

 apertures likewise of roundish or oval shape are added to them 

 until the largest occurring in the deepest part of the cavity may- 

 measure 1'") mm. or more across. Centrally at the bottom there 

 is an irregular space with comparatiyely small apertures, as we 

 haye seen also in C. weyeri. The larger apertures usually do 

 not lie very close together but are separated from one another 

 by a rather wide interspace occupied l)y small apertures only. 

 While the smaller apertures show a sharp angular edge, the 

 larger ones are without any edge at all, the transition of the 

 central gastral cavity into the excurrent passages being gradual 

 and imperceptible. The latter are sometimes shallow and niche- 

 like, at other times much deeper and pit-like or canal-like. The 

 appearance of their wall is essentially that of an extension of the 

 gastral surface. The larger deeply penetrating excurrent canals, 

 as can be determined by cutting them open, often but not always 

 intercommunicate with one another. The anastomosis reminds 

 one strongly of the gastrocanals or the tubar system of the 

 Ascons. It is plainly associated, both genetically and in topo- 

 graphical relation, with the intercanal system of the exterior. 



The stalk is nearly as long as, and sometimes perceptibly 

 longer than, the body proper. In general appearance it is 

 scarcely distinguishable from that of C. meyeri. It is firm 

 throughout, the lower part being quite hard and compact. The 

 lower end may expand into an attachment disc. Superiorly it 

 gradually broadens, acquiring a densely and longitudinally fibrous 

 appearance and an obtusely polygonal shape in cross-section. 

 On severing the sponge-body, the upper end of the stalk is found 

 to he divided into a few l)ranches ; so, at any rate, after the 

 sponge has attained a large size. It is solely by this peculiarity 



