SPONGES. 31 



of Asjjergilkim. Of course^ as the nuclei of valves could 

 not be found,, and as the whole texture of the tube was 

 an open network of sponge, instead of a tubular lamina 

 of shell, the illusion w^as soon dissipated. The tube is 

 gently curved, like a horn, but not coming to a point, and 

 at the base it is two inches wide. Here it is covered by 

 a disc of very open network, outwardly convex, and sur- 

 rounded by a thin projecting frill or plate of plaited fibres. 

 In the wall of the tube there are supporting fibres placed 

 lengthwise, and forming the upright framing upon which 

 the cross fibres are woven. There are three sets of cross- 

 fibres in different directions ; two spiral, opposing and 

 crossing each other diagonally, and the tliird, horizontal. 

 These cross each other in such a manner as to form cir- 

 cular holes, between the upright supports, at regular in- 

 tervals. Between the diagonal rows of holes, the paries 

 is further strengthened and beautified by diagonal frills 

 resembling that which bounds the terminal disc; at the 

 smaller end the longitudinal supports separate into the 

 minute fibres of which they are composed, and meeting 

 round the orifice blend into a wool-like fluff. A figure of 

 this beautiful object is published, witli Professor Owen^'s 

 description, in the ' Transactions of the Zoological Society.' 



