200 On Ceratopora, the Type of a New Family of Alcyonaria. 



If Ceratopora is an Alcyonarian, it is necessary to consider what position it 

 should occupy among the orders of its sub-class. 



The long, isolated spicules do not afford a satisfactory character for tbe- 

 determination of its affinities, and although the spicules of one of the 

 Stolonifera have some resemblance in arrangement and shape to the spicules 

 of Ceratopora, this resemblance can be regarded only as an example of con- 

 vergence. The massive crystalline skeleton in which the spicules are 

 imbedded seems to indicate close affinities with Heiiopora, the only recent 

 Alcyonarian in which such a type of skeleton occurs. It is possible, of 

 course, that this type of skeleton may have arisen independently within the 

 sub-class, as we have examples of non-spicular calcareous skeletal structures 

 in the axis of the Gorgonellidse and in the axis of some of the Pennatulacea 

 among recent Alcyonaria, and possibly also in the thecal walls of Syringo- 

 pora, Favosites, and the Heliolitidae among the fossil corals that are supposed 

 to have Alcyonarian affinities. 



But this type of skeletal structure, combined with the fusion of the thecal 

 walls to form a honeycomb arrangement of the tubes, may be regarded as 

 sufficient to justify the inclusion of Ceratopora in the order Coenothecalia, k> 

 which Heiiopora belongs. Nevertheless, Ceratopora differs from Heiiopora in 

 many important respects, and of these the most interesting is the presence of 

 spicules, for in this respect the genus may be regarded as intermediate between 

 the Coenothecalia and the Stolonifera. 



The monomorphic condition of the pores, the absence of tabulse. and the 

 complete closure of the tubes below by the continuous growth in thickness of 

 the thecal walls, are further characters of importance that separate the two* 

 genera. On these grounds Ceratopora must be regarded as the type of a new 

 family of Coenothecalia, which may be defined as follows : — 



Geratoporidce. New Family. 



Coenothecalia forming a massive skeleton of crystalline calcium carbonate, 

 in which a few slender spicules are imbedded. No tabulse, the tubes closing 

 below by the continuous growth of the thecal walls. Pores monomorphic 

 and small (in the type species - 2 mm. in diameter). 



Ceratopora nicholsonii, new genus and species. — Off Ciba, 100 fathoms. 



