358 J. E. Dueeden — Jamaican Actiniaria : Part I. — Zoanthece. 



polyps being raised above the general level of the coenenchyme ; in another part 

 the polyps may be quite free for a few millimetres. Again, colonies would 

 be collected which became quite flat on their distal surface, due to excessive 

 retraction as a result of rough handling ; but, on coming to observe them later, 

 the polyps had elevated the upper part of their column distinctly above the level 

 of the coenenchyme, and the whole presented a very different aspect. Such 

 variations have also been noted as occurring on the same colony at one and 

 the same time. The dimensions, especially the height of the column and 

 coenenchyme, are also very variable, depending largely upon the irregularities 

 of the incrusted rock and the presence of contiguous colonies ; one side of a 

 colony may be two or three times the height of another. 



The colour is so very similar in all the Jamaican forms I have examined as 

 to be of little assistance. So far I have only met with various tints of yellow and 

 brown ; a colony which appears yellowish in the water may become brown on 

 removal. Transverse and longitudinal wrinklings are largely determined by the 

 amount of shrinkage in preservation ; alcohol material showing more than forma- 

 lin. The number of tentacles has been used by Duchassaing and Michelotti as 

 an important aid in distinguishing species. Generally, this can only be of service 

 where one is able to study the forms in the living condition, most colonies appear- 

 ing to prefer a retracted state after removal from their natural habitat. I have 

 generally found that unless much injured in removal, the polyps open out suffi- 

 ciently for investigation during the first day in the laboratory, and plunging into 

 formalin has fixed them in this condition. I have studied the capitular or marginal 

 ridges more particularly when the polyps have been thus partially or completely 

 open. In the numerous cases counted, the ridges were always found to corre- 

 spond with half the total number of the tentacles, i.e., with one cycle. 



Although varying somewhat, there is no doubt that the ridges and tentacles are 

 of considerable utility for systematic purposes. How far they may be depended 

 upon will be seen from the following observations made specially upon numerous 

 colonies from the various Cays to test the reliability of the character. Each of 

 the letters indicates a separate colony, or portion of one, and the figures the number 

 of ridges counted upon the individual polyps sufficiently open for the purpose. 



Lime Cay : 



A.— 15, 13, 16, 16, 15, 15, 14, 15, 14, 16, 14, 15, 14, 16, 14, 15, 14, 14, 16. 



B.— 19, 20, 19, 20, 19. 



C— 20, 19, 19, 20, 20. 



D.— 22, 19, 19. 



E.— 14, 14, 13, 14, 14, 15, 15. 



South Cay 



F.— 14, 14, 14, 14, 14, 15, 14, 16, 14, 16. 

 G.— 18, 18, 18, 18, 19, 18, 18, 17, 19, 18, 18. 

 H.— 18, 18, 19, 18, 18. 

 I.— 18, 19, 18, 17, 19. 



