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XIV. 



JAMAICAN ACTINIARIA. Part I.-ZOANTHE.E. By J. E. DTTERDEN, 

 Assoc. R.O.Se. (Lond.), Curator of the Museum of the Institute of Jamaioa. 



(Plates XYII. a, XVIII. a, XIX., XX.) 



[Kead March 24, 1897.] 



The following account, restricted to the well-defined group of the Zoantheae, is 

 a first contribution from investigations now being carried out upon the Jamaican 

 Actiniaria. It is remarkable that, with the exception of two species of Palythoa, 

 collected by Sir Hans Sloane, probably about the year 1687, no Actinian has, so 

 far as I can ascertain, been recorded from the island. Thanks to the labours of 

 MM. Duchassaing and Michelotti (1850, 1860, 1866), and to the later researches 

 of Professor M°Murrich (1889, 1889 a, 1896), we are acquainted with numerous 

 examples from the other West Indian Islands, with which the Jamaican forms 

 may be compared. These are proving that the Actinian fauna of the whole 

 Caribbean region presents no marked difference. Professor M c Murrich has shown 

 this for the Bahamas and the Bermudas, and of thirty- four Jamaican species 

 now known, nearly all are forms recorded from one or more of the other islands 

 of the Antilles. With the exception of the valuable work contributed by 

 M c Murrich, practically no studies on Western forms have been conducted along 

 the modern anatomical lines instituted and carried out elsewhere by Hertwig, 

 Erdmann, Haddon, and others. Hence the necessity that the different repre- 

 sentatives, many only partially known, should be submitted to microscopical 

 examination to enable them to be arranged in the later systems of classification. 



The following definition of the group of the Zoanthese is the one given by 

 Professor Haddon and Miss Shackleton (1891), and is practically the same as that 

 accepted by all recent writers : — 



ZO ANTHER. 



Actiniae with numerous perfect and impex'fect mesenteries, and two pairs 

 of directive mesenteries, of which the sulcar are perfect and the sulcular are 

 imperfect. A pair of mesenteries occurs on each side of the sulcular directives, 

 of which the sulcular moiety is perfect and its sulcar complement is imperfect ; 

 a similar second pair occurs in one section of the group (Brachycneminse), or the 



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