CHAP, vii.] THE 1)EEP-$%A FAUNA. 425 



of the sponge. Such an association is undoubtedly 

 artificial. 



Dr. Bowerbank, another great sponge authority, 

 takes yet another view. He maintains "that the 

 silicious axis, its envelopment, and the basal sponge 

 are all parts of the same animal. 5 ' The polyps 

 he regards as ' oscula,' forming with the coil a 

 ' columnar cloacal system.' 



Professor Max Schultze, of Bonn, examined with 

 great care several perfect and imperfect specimens of 

 Hyalonema in the Museum of Ley den, and in 1860 

 published an elaborate description of its structure. 

 According to Schultze, the conical sponge is the 

 body-mass of Hyalonema, a sponge allied in every 

 respect to Euplectella ; and the siliceous coil is an 

 appendage of the sponge formed of modified spicules. 

 The zoophyte is of course a distinct animal altogether, 

 and its only connection with the sponge is one of 

 ' commensalism.' It 'chums' with the sponge for 

 some purpose of its own, certainly getting support 

 from the coil, probably sharing the oxygen and 

 organic matters carried in by the ciliary system of 

 the sponge passages. This style of association is 

 very common. We have another example of the 

 same thing in Palythoa axinellce, SCHMIDT, a con- 

 stant ' commensal ' with Axinella cinnamomea and 

 A. verrucosa, two Adriatic sponges. 



In 1864 Professor Barboza du Bocage, director 

 of the Museum of Natural History in Lisbon, com- 

 municated to the Zoological Society of London the 

 unexpected news that a species of Hyalonema had 

 been discovered off the coast of Portugal ; and in 1865 

 he published, in the Proceedings of the same Society, 



