186 J. E. DuERDEN — Jamaican Actiniaria : 



occurs also in the proximal region of many Actiniaria after the ciliated streak 

 has ceased to exist. 



The mesogloeal axis of the mesentery, comjoletely surrounded by a weak 

 musculature, passes into the base of the filaments, and there becomes slightly 

 expanded, sending a branch to each side. The cells on the anterior or inner 

 border are much longer than on the sides and behind. They are mostly 

 strongly ciliated supporting cells, with which are mingled glandular cells of 

 various kinds, and large oval nematocysts with a loose internal thread. The 

 latter are of the same form as occur more rarely in the ectoderm of the stomodaeum 

 and knobs of the tentacles. 



In the stomodseal region the imperfect mesenteries are devoid of filaments ; they 

 appear, however, immediately below and completely resemble those on the chief 

 mesenteries. 



Proximally the mesentei'ies branch at their free termination, each branch 

 being capped by a filament in which the large nematocysts predominate. 



No gonads were present in any of the polyps examined. 



On one occasion six specimens were collected at Drunkenman Cay, all closely 

 associated within a crevice in the coral rock in shallow water ; and another time 

 several polyps were come upon living together on a live Pinna shell from Harbour 

 Head, Kingston Harbour. When irritated they are capable of sending out 

 quantities of clear mucus. 



The species was first obtained by Duchassaing and Michelotti from St. Thomas, 

 and described by them under the term Draytonia myrcia ; Andres places it among 

 his " Corynactidfe dubias," under the genus Corynactis. The correctness of this 

 generic transference I have already referred to. 



Its histological characters should be compared with those of C. australis (1896, 

 pp. 152-3), and it will be seen that the two closely agree. The mesenteries 

 are, however, more regular, and the sphincter muscle slightly better developed in 

 the present species. The sphincter also differs from that of C. viridts, AUm. (1896, 

 pi. viii., fig. 11). 



The connexion of one polyp with another by a basal expansion, and the usual 

 occurrence in groups are indicative of asexual reproduction, a method already 

 known to occur in the British Globehorn, C. viridis (1860, p. 291). The 

 irregularities in the arrangement of the mesenteries noted in C. australis (1896, 

 p. 152), and in C. hojMtes (1898, p. 468), are probably also due to this process. 

 In the Australian representative it was found that some specimens possessed only 

 one pair of directives, while others had two. 



Attention should be directed to the tetrameral arrangement of the mesenteries, 

 corresponding with the tetrameral tentacles ; the extraordinary development of 



