DIE ALCYONIDEN DER SIBOGA-EXPEDITION 
I €EORAELIDZE 
BY 
SYDNEY J. HICKSON M.A,., F.R.S,., 
Professor of Zoology in the Victoria University of Manchester. 
With one plate. 
Family Corarrnp.e Gray emend. Ridley. 
Corrallide Gray, Proc. Zool. Soc. 1857, p. 286. 
Coralline Milne Edwards, Hist. Nat. Corall. t. 
17, pP. 201. 
Corallüd® Ridley, Proc. Zool. Soc. 1882, p. 221. 
The family Coralliide is distinguished from the other families of the sub-order Pseudaxonia 
by the hard calcareous imperforate axis formed by the growth and adjustment of the spicules 
of the deeper layers of the coenenchym accompanied by a calcification of the intervening 
mesogloea. In the Sclerogorgiidae there is also a distinct imperforate axis but the long spindle 
shaped spicules of which it is built up are surrounded by a sheath of horny substance which 
renders the axis more flexible than it is in the Coralliide. In the Briareide the axis is porous. 
The manner in which the hard axis of Corallium is formed has been studied by pr Lacaze- 
DurHiers (4), KÖLLIKER (3), NıcHoLson (6) and Funasasuı (3). According to DE LAcAzE-DUTHIERS 
it is formed of two elements, the spicules and the cement, or as it was expressed by KörLıkEr 
l.c. p. 147: “Die Axe von Corallium durch die Vereinigung von Kalkkörpern und einer ver- 
kalkten Zwischensubstanz entsteht’. 
When the axis is dissolved slowly in weak acids, according to Fuxasastı, a spongy organic 
substance is left behind, and when this is examined by the microscope it is found to consist 
entirely of the empty sacs of spicules, without any other cementing substance 
Eu 
between them. 
The interpretation of these investigations appears to be that the spicules of the coenen- 
chym, when they have reached their full size and are seated in the inner or deeper layers of 
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SIBOGA-EXPEDITIE XIII.€- I 
