f 329 J 
XIV. 
JAMAICAN ACTINIARIA. Parr I.—ZOANTHEM. By J. E. DUERDEN, 
Assoc. R.C.Se. (Lond.), Curator of the Museum of the Institute of Jamaica. 
(Prares XVII.a, XVIII.a, XIX., XX.) 
[ Read Marcu 24, 1897. | 
Tue following account, restricted to the well-defined group of the Zoanthez, 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* 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*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 Zoanthez is the one given by 
Professor Haddon and Miss Shackleton (1891), and is practically the same as that 
accepted by all recent writers :— 
ZOANTHEA. 
Actiniz with numerous perfect and imperfect 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 suleular moiety is perfect and its sulcar complement is imperfect ; 
a similar second pair occurs in one section of the group (Brachycneminz), or the 
TRANS. ROY. DUB. SOC., N.S. VOL. VI., PART XIV. 3 E 
