23 



sponge were brought from Japan, but within the last few years 

 other habitats have been discovered. Professor Perceval "Wright 

 found it in situ in Setubal, off the coast of Portugal, in 1868, 

 obtaining many fine specimens from the same locality, and had 

 the opportunity of examining them whilst alive. He states that 

 the silicious stem is truly part of the sponge mass, and that the 

 " Polythoa " (bark) was simply parasitic upon the stem. Some 

 of the Setubal specimens were very large, the stems of several 

 measuring nearly two feet in length, and the head consisting of 

 a somewhat oval mass about eight inches in the long, and four 

 inches in the short, diameter. On opening out the sponge the 

 interior concave surface was found to be lined with a delicate 

 network of spicules and sarcode. A number of large openings 

 (oscula) were also seen, and these were covered with a network 

 of sarcode, and the edges of the meshes thickly covered with 

 spicules, called by Dr. Bowerbank " spiculate cruciform spicules." 



The Professor then goes on to say that he has "seen the 

 parasitic polythoa in a living state on the silicious axis of the 

 Hyalonema, and that he watched the polyps expand their tentacles, 

 after the fashion of any other zoantharian, to prove that, though 

 they have mouths, these mouths are their own, and not at the 

 service, directly or indirectly, of the Hyalonema" Dr. Bower- 

 bank is, however, of opinion that the Polythoa is a portion of 

 the sponge, and not parasitic : " The evidences in favour of the 

 latter supposition are (at least as far as I have been able to ascer- 

 tain) first, that the glass rope has never been found without 

 the ' bark ;' secondly, the spicules are silicious (in all other spicule- 

 bearing species of Polythoa they are calcareous), and that some 

 of them are common to every portion of the sponge; neither 

 am I aware that the Polythoa has ever been found investing any 

 other organism." 



The spicules in this sponge are perhaps more beautiful and 

 varied than in any other sponge hitherto discovered. Mr. F. 

 Kitten then proceeds to figure and describe the spicules, adopt- 

 ing the terminology used by Dr. Bowerbank in his work on the 

 British spongiada. He then says, " Having had an opportunity 



