268 Dr. J. E. Gray on Hyalonemata. 



twenty additional specimens, which he has just purchased, to 

 examine. Twelve of them are imbedded in larger and smaller 

 fragments of sponge ; and the coils vary greatly in diameter 

 and length, and in the quantity of bark on them. Two belong 

 to the free variety ; one is not in a good state : the other con- 

 firms me in the opinion that the HyalochcBta Possieti^ figured 

 by Brandt, is a free variety; for it nearly resembles this figure; 

 but the polypes are not quite so long nor quite so much 

 clustered. 



When examining these specimens I was induced to re-study 

 the whole question and to re-read Professor Max Schultze's 

 well-reasoned and very interesting paper on the genus in the 

 ' Annals & Mag. Nat. Hist.' for March 1867 (xix. p. 153), and 

 made the following notes, feeling satisfied that Prof. Schultze, 

 like myself, is only desirous of arriving at the truth as to the 

 structure of this most interesting marine production, and that 

 we chiefly dififer from observing the specimens in different 

 states and from a dififerent point of view. 



I think that Prof. Max Schultze overestimates the simi- 

 larity of the Palythoa on the Axinella and the animal of Hya- 

 lonema. The Axinella is not ^^ always covered with this para- 

 site;" the animals are scattered singly or in groups on the sur- 

 face of the sponge, forming irregular tubercles, which caused 

 Esper to call the sponge Spongia tuherculata. I cannot con- 

 sider it " the most perfect analogy to the parasitism of Palythoa 

 fatua in Hyalonema ;" there the polypes form a uniform con- 

 tinuous bark, the inner coat of which surrounds each of the 

 siliceous spicules with a sheath of corium. (See Brandt, t. 4. 

 f. 14.) 



There can be no doubt that the idea of our Hyalonema being 

 a sponge arose in MM. Valenciennes and Milne-Edwards 's 

 minds from the examination of very imperfect specimens ; for 

 the latter states that " the polypes, which we have observed in 

 a dry state on different parts of the axis^ appear to be only 

 parasites belonging to the order Zoantharia." One of the 

 three figured in Prof. Schultze's work is destitute of any bark ; 

 and the other two only have very small quantities of the bark 

 on the coil near the sponge. Well-preserved specimens gene- 

 rally have about half the length of the coil covered with ani- 

 mals. They seem more abundant in England than on the 

 Continent. I have had through my hands, since I first de- 

 scribed the genus in 1835, between 300 and 400 specimens. 



Dr. Max Schultze observes : — ^^ Thus, therefore, we have 

 every imaginable proof of the mutual relation of the ^ Glass 

 Bope ' and the sponge, which may be briefly recapitulated as 

 follows : — 



