Sfmpson— yl Revision of the Gorgonelliihie. 273 



coenenchyma differentiated into a cortical and medullary ijortion, the latter 

 containing spicules different from tliose of the cortex, densely crowded 

 together, and sometimes cemented together to form a siqjportiriff axis." 



One of the families of this order — namely, the Sclerogorgidae — is thus 

 defined : — " The medullary mass forms a distinct axis, consisting of closely 

 packed, elongate spicules, with dense horny sheaths. The axis does not 

 contain solenia, but is surrounded by longitudinal canals — i.e., by large 

 solenia — which are connected with the zooid cavities by ramifying solenia." 

 Of the genus Suberogorgia, Gray, in his original description (Proc. Zool. Soc.> 

 1857, p. 159), says: — "Axis pale-brown, formed of rather loosely concentric 

 fibrous laminae, containing a large quantity of calcareous matter." 



From the Pseudaxonia the Axifera are thus difl'erentiated : — " Synal- 

 cyonacea forming colonies consisting of a coenenchymatous rind, investing a 

 horny or calcified axis. The axis may be horny or composed of a calcified 

 horny substance. ... It never contains solenia, and is never formed of fused 

 spicules. The coenenchyma completely invests the axis, and contains solenia, 

 and calcareous spicules embedded in the mesogloea." 



Bourne does not include the Gorgonellidae in his scheme of classification ; 

 and as the nature of the calcareous constituent in this family has never been 

 investigated, or even commented upon, it is impossible to say whether they 

 are Pseudaxonia or Axifera. 



The time at our disposal has not permitted of a detailed investigation 

 of this very important problem ; but as a contribution to this stutly the 

 following observations may be useful : — 



Suberogorgia. — An examination of the axis of a specimen of this genus 

 reveals the following features : — 



(1) It consists of a horny matrix, in which large irregular spicules are 

 embedded longitudinally. These spicules are easily seen with a strong lens, 

 and appear to be deposited concentrically. 



(2) The axis after decalcification retains its original shape. 



(3) Prolonged boiling in caustic potash causes a slight disintegration ; and 

 the individual spicules may thus be separated. 



(4) The spicules of the axis are quite different from those of the 

 coenenchyma. 



(5) A thin horny layer may be detached from the axis, in which the 

 spicules may be seen embedded. 



Juiieella elongata var. capensis. — Hickson (xiii.) described an Alcyonarian 

 from Cape Colony under this name, but at that time the spicules of this 

 species were unknown. Subsequent study, and a consequent resuscitation of 



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