3 6 THE SPONGES 



from 90 to 3,000 fathoms, and characterised by having the skele- 

 ton built up of siliceous spicules, each typically possessing three 

 axes and six rays, or of spicules derived from such a type. To 

 this class belongs the beautiful Venus' s Flower Basket (Euplectella 

 aspergillum), which forms a most wonderful lattice-like skeleton, 

 shaped like a graceful cornucopia. It is obtained from a depth of 

 some 90 fathoms off Cebu in the Philippine Islands, while another 

 and much larger form (Euplectella imperialis) comes from Japan. 

 Another interesting example, the Glass Rope Sponge (Hyalonema 

 sieboldii), is obtained by the Japanese deep-sea shark-fishers, by 

 means of hooks attached to their deep-sea lines. The " glass 

 rope," or twisted strand, which is such a striking feature of this 

 Sponge, is really a root-tuft composed of immensely long spicules, 

 which terminate in toothed grapple-like discs, and securely anchor 

 the Sponge in the mud. When these root-strands were first 

 brought to Europe, without the body of the Sponge attached, they 

 were thought to be artificial productions. The body of the Glass 

 Rope Sponge is somewhat like a closed cup in shape, the walls of 

 loose texture and comparatively soft to the touch, and with large 

 and small circular openings, which connect with the interior. The 

 beautiful Lace Sponge (Semperella schultzii) also belongs to this 

 class, and has a straight or curved cylindrical and somewhat conical 

 body, the upper surface of which shows a delicate, fine lace-like 

 network, with bands and patches of a coarser pattern. 



The class Demospongise includes all sponges other than the 

 Calcareous and Hexactinellida. Familiar examples are the huge 

 Neptune's Cup Sponge (Poterion patera), which comes from the 

 East Indies and is one of the largest of the Sponges ; the Sea- 

 Kidney Sponge (Chondrosia reniformis) ; the curious Boring 

 Sponge (Cliona), which excavates extensive galleries in oyster 

 shells, so that a shell may often appear to be covered with small 

 round holes ; the Horny or Bath Sponges ; the Slime Sponges ; 

 and the Freshwater Sponges. The Encrusting Sponges are some- 

 times a great pest on the oyster grounds, as they grow over the 

 shells of the oysters and starve the inhabitants by capturing the 

 food particles floating in the water, which would otherwise reach 

 the unfortunate molluscs. To get over this trouble, in some places 

 the oysters are grown on frames, which from time to time are 

 drawn above the surface of the sea and left exposed during a 



