Dr. J. E. Gray on Hyalonemata. 273 



there are concentric ridges edged with a series of spines that 

 are directed towards the middle of the length of the spicule. 

 (Schultze, t. 2. f. 4, 5). These spicules are lengthened as the 

 coral grows. 



The corals live erect at the bottom of the sea, with the free 

 part of the spicules sunk in the mud or sand. 



The upper part of the coral is often taken possession of by 

 a cup-shaped parasitic sponge {Carteria), The sponge de- 

 stroys the polypes ; and the ends of the spicules form a short 

 rapidly tapering cone, which is separated from the sponge 

 by a number of spicules felted together, forming a hard case 

 which separates the end of the coil from the rest of the sponge. 



The coils of spicules, as left when the polypes die and the 

 bark has rotted or been eaten away by fishes, &c., are often 

 found in the sea, as are also the separate spicules. 



M. Bocage makes a statement that is otherwise difficult 

 to understand. He says, " I have several specimens of Hyalo- 

 nema with other parasites : two are covered with an Antipa- 

 tharian, three absolutely destitute of polypes and sponges, 

 one embraced by the foot of an Actinia of what seems to me a 

 new species." (Ann. & Mag. Nat. Hist. ser. 4. vol. ii. p. 37.) 

 Dr. Semper has lately named a single specimen of Hyalonema 

 he received from the Philippines H. Schultzei^ because it is 

 destitute of polypes and bark, but attached to a sponge. 



They have been found in a fossil state in Mountain Limestone, 

 retaining the siliceous character of the coil. 



Hyalonema, Gray, Proc. Zool. Soc. 1835, p. 64 ; Ann. & 

 Mag. Nat. Hist. 1850, vi. p. 306; P. Z. S. 1867, p. 118 

 (not Loven, Ann. & Mag. N. H. 1868, p. 90) ; Brandt, Svm- 

 boi. 14 (1859) ; Wyville Thomson, Intell. Observ. 1867, p'^81. 

 Hyalochceta, Brandt, Bull Acad. P^tersb. 1857, p. 17 ; Symbol. 17 (1859). 



Bark sandy. Polypes cylindrical when contracted. Tenta- 

 cles 20. 



1. Hyalonema Sieboldii^ Gray, P. Z. S. 1835, p. Qt5y &c. B.M. 



H. mirabUis, Gray, P. Z. S. 1857, p. 279 ; Bowerbank, P. Z. S. 1867, p. 18; 

 Loven, Ann. & Mag. N. H. 1868, p. 90. 



Type^ without parasitic sponge on apex : — 



H. Sieholdii, Brandt, Symbol. 1. 1. f. 1 ; Wyville Thomson, Intell. Observ. 

 1867, p.93,f.l. 



Var. Possieti. Polypes produced and clustered. 

 Hyalochmta Possieti, Brandt, Symbol, t. 2. f. 6-20. 



separate the siliceous spicules of zoanthoid polypes from the r^picules of 

 sponges. 



