Pore-area of Cliona corallinoides. 15 



them, as required — a process which, of course, is very slowly 

 effected, on account of the amoeboid nature of the sarcode ; so 

 that, on death occurring suddenly (that is, where the sarcode 

 has not become putrid and passed into dissolution, and there 

 has been no time for closing by reflex action) these apertures 

 remain. Hence in dried specimens, where the dermal sarcode 

 is not destroyed, they remain visible. 



There are two kinds of openings, viz. the pores and the 

 vents — the inhalant and exhalant apertures. 



Directing our attention to the former first, we find them 

 averaging about a 1000th of an inch in diameter, — either scat- 

 tered generally over the dermal sarcode opposite the interstices 

 of the subjacent spicular structure, as in the Esp&riadse, Hali- 

 chondria panicea, Johnston, &c., and the CalcispongiEe ; or 

 confined to circular areas in juxtaposition, as in Raphyrus 

 Grijfithsiij Bk. [Cliona celata?)^ Raphiophora patera^ ^^^Jt 

 or Neptune's Cup, Pacliymatisma^ &c. ; or to circular areas 

 separated from each other and raised on cylindrical heads, as 

 in Grayellacyaihophora^ Cart., Cliona corallinoides^ Hancock, 

 &c. 



Of these the Clionidge, including Raphyrus and Rapliiopliora 

 (see " Mdm. sur le Genre Poterion^'' par P. Harting, Soc. des 

 Arts et des Sci. d'Utrecht, 1870, pi. 4. figs. 7 & 12), present 

 examples of a division of the sponge-structure in the pore-areas 

 resembling the tentacular head of a polype ; but as this is 

 merely a resemblance, and my object in introducing the sub- 

 ject of the openings in the sarcode of the Spongiadse is more 

 especially to show this, I shall take Cliona corallinoides alone 

 (PI. II. fig. 33) for description and illustration, as affbrding 

 the nearest resemblance of this kind that I have met with. 



This sponge (like Raphyrus Griffithsii and the great Nep- 

 tune's Cup, together with the diminutive Grantia ciliata 

 and its like among the calcareous sponges) possesses no 

 branched system of excretory canals like most of the other 

 sponges, but consists merely of an areolar structure (PI. II. 

 figs. 33 & 36, a a) which, burrowing between the layers of 

 univalve and bivalve shells, forms for itself therein similar 

 excavations, which open into each other by efferent (fig.36,ccc) 

 and afferent apertures, finally communicating with the exterior 

 by distinct heads (figs. 33, a, &, & 36, h) here and there, most 

 of which are simple pore-areas (fig. 34), while the rest present 

 a combination of vent and pores (fig. 35) or a single large 

 vent only. Cliona corallinoides not only excavates shells, but 

 the sandstone rock too of this locality, where it shelters itself 

 under the florid expansions of Melohesia lichenoides^ which 

 goes on growing (that is, spreading in all directions), while the 



