BRITISH SPONGIADiE. 63 



not one of them in the dried state is there any indication 

 of a terminal aperture. Professor King told me, " that the 

 colour when alive was the same as in the dead specimen. 

 That it was stiff and rigid when alive, and that no aper- 

 tures were visible on the mammas." In tbeir dried con- 

 dition they are strap-shaped by collapse ; the largest of 

 them are three lines in breadth at the base, and gradually 

 tapering upward, terminate in obtuse cones. 



At the base, within each of the fistulas, there is a tolerably 

 stout, contractile membranous diaphragm; in one case 

 examined, the membrane was entirely closed, in another 

 there was a circular opening in the middle of it, equal to 

 about one fifth or one sixth of the whole diameter, and in 

 a third case the orifice in the diaphragm was equal to about 

 half its entire diameter. It is evident, therefore, that the 

 animal has a perfect control over the action of the fistulas, 

 and as each of these organs are furnished with pores on all 

 parts of their parietes, so they also have the power of in- 

 dependent inhalent and exhalent action, as well as the 

 parent mass of the sponge. This power of regulating the 

 vital action in one part of the sponge, independent of 

 another part, is quite in accordance with a similar capability 

 of suspension or alternation of action in the oscula of 

 Hymemacedon caruncula, which I have described in my 

 paper on the vitality of the Spongiadas, published in 

 the Reports of the British Association for 1856, page 

 438. 



The anatomy of the fistulas of this sponge, especially 

 that of the nbro-membranous tissues, exhibits a high 

 degree of organic structure, and indicates an amount and 

 variety in the powers of action in these organs, unusual 

 among the Spongiadas. It is unnecessary to notice the un- 

 usually complex structures of these tissues at length, as 

 they are sufficiently described at p. 100, in the first volume 

 of this work. A specimen of this species, about two and 

 a half inches long, and not exceeding nine lines in breadth, 

 detached from the body on which it grew, was dredged 

 three miles off Dunstanborough, Northumberland, and was 

 sent to me for examination by the Rev. A. M. Norman, in 



