THE ALCYONARTA OF THE CAPE OF GOOD HOPE AND NATAL. 563 



It "appears, however, that between these different types or varieties of coloration, 

 there are intermediate stages grading the one into the other. 



The polyps show themselves on the surface of the "pileus" in varied degrees of 

 expansion and contraction. A number of young polyps are present between the 

 better developed ones. The polyps are capable of being withdrawn within the eight- 

 partite calyx. On retraction, the tentacles are drawn down, but are not inverted. The 

 number of pinnules in the tentacles was not observed. 



It was fairly easy to remove well-expanded polyps out of their canals, and as they 

 are fairly transparent, their structure is readily understood. The polyp is differentiated 

 externally into three parts : 



1st, A crown and tentacles with long spindles arranged en chevron in eight 

 more or less triangular stripes. These eight longitudinal stripes unite more or 

 less at their bases into a ring of spicules, which encircles the upper part of the 

 polyp. This circular band is not well developed, consisting only of a few spicules 

 horizontally or obliquely disposed. 



2nd, A stomodseal part, with small spicules in the wall of the stomodaeum 

 (proper). 



3rd, A part containing the mesenterial filaments, and devoid of spicules. 



The calyx projects on the surface of the coenenchyma as a ring containing small red 

 spicules. The calyx has an outer and inner wall, both containing spicules, but the 

 outer wall has a larger number. The outer and inner walls of the calyx are trans- 

 versely connected with one another at intervals by small tubes. The calyx is 

 retractile. 



The colours of the polyps are produced by the spicules ; those of the tentacles are 

 yellow or red, or yellow and orange apically, and red ones at the base. The spicules of 

 the stomodseum (proper) are also yellow or red, and those of the calyx are yellow, red, 

 or orange. 



The muscles in the stomodaeal part of the polyp are extremely large ; in some cases 

 they fill up at least half the space of the intermesenterial cavities. The siphonoglyphe 

 is broad and ciliated, and directed, in all observed cases, towards the exterior or away 

 from the centre of colony. The ectodermal wall of the stomodseum is thick, the 

 mesogloea extremely thick, and the endoderm thin. The cavities of the polyps are 

 continued directly downwards into the canals running down through the trunk. 

 In the globular head, there exists a distinct coenenchyma between the polyp 

 cavities ; but in the trunk region this is not so, as the walls between the canals 

 are very thin. 



A rough transverse section through the " pileus " shows an extremely large number 

 of spicules, especially in the outer part. These spicules are long, spinous spindles or 

 needles. One of these measured as much as 0'816 mm. in length. The long spindles 

 are, as a rule, disposed radially ; besides these, there are also a few short spicules. A 

 rough section through the trunk shows again a very large number of spicules, but they 



