THE PUMICE-STONE SPONGE. 



771 



knowledge of the subject, they can hardly ever be made to believe that the exhibitor is 

 not endeavouring to play a practical joke upon them. 



The Neptune's Cup is of enormous dimensions, often measuring four feet in height 

 and having a corresponding width. Its exterior is rough, gnarled, and knotted like the 

 bark of some old tree ; and if a portion were removed from the side, it might almost be 

 mistaken for a piece of cork-tree bark. Many persons have imagined that the strangely- 

 shaped object was made of the skin of an elephant's leg, and I have even heard a teacher 

 telling her pupils that it was an old Eoman wine-jar. 



It is hardly possible to disabuse strangers of the notion that it is not the result of 

 human ingenuity until they are allowed to lift it, and test personally its exceeding 

 lightness. It is hollow, and is not at all unlike an old font that by some misfortune has 

 been deprived of its base. Its capacity is enormous, and it would not only form a cup 

 for Neptune, but even Polyphemus himself might have filled its depths with the ruddy 

 wine which he loved, and failed to empty the huge vessel at a draught. 



The substance of this enormous sponge is porous, rather stiff, and without much 

 elasticity. It yields but slightly to pressure, and almost feels to the touch as if it had 

 been made from cork. 



This is one of the exotic Sponges, being found only in the hotter seas. In general 

 shape it has some resemblance to the Funnel-sponge already described, but is of much 

 coarser texture, and, save for its gigantic size, is not nearly so attractive. 



PUMICE-STONE SPONGE. - Dactylochalix pumicea. 



IN the PUMICE-STONE SPONGE, we have an admirable example of the flinty structure 

 developed to the utmost degree. The framework is wholly composed of flinty spiculse, 

 all fused together, and forming a highly porous mass, which at first sight resembles a 

 madrepore rather than a true Sponge. It has not the least elasticity, but is as hard and 

 as stiff as if it had been carved from stone. On account of its extreme porosity, it is very 

 light, seeming to weigh not more than a piece of cork of the same size. 



The whole surface, above and below, is plentifully sown with pores, which have a 

 lovely effect under a magnifier, when the sunbeams fall on the glittering spiculse of which 

 the mass is composed. A number of the large apertures appear on both sides, and all 

 converge towards the centre. The general shape of this remarkable Sponge is cup-like, 



