J. E. Dueeden — Jamaican Actiniaria : Parti. — Zoanthew. 371 



macrocnemic arrangement, occur in one specimen, and are all very thin except 

 near their origin and where fertile ; the imperfect are very short ; the parieto- 

 basilar muscle is developed along each side ; no basal canals, or only traces of 

 them, are present. The mesenterial muscles are seen on slight plaitings; pigment 

 granules occur in groups on the endoderm. The digestive endoderm is thick, and 

 large oval nematocysts are embedded in it, along with groups of pigment granules. 

 The imperfect mesenteries have the muscle fibres extending all round. In the 

 distal region, just below the oesophagus, the mesoglcea at the origin of the mesen- 

 teries is rectangular, but proximally it becomes goblet-shaped, the part produced 

 beyond in perfect mesenteries being extremely thin. Proximally the mesenteries 

 are branched. 



Gonads (PI. xx., fig. 4). — Spermaria apparently enclosed in endoderm were 

 met with in abundance in two specimens. 



This species is most closely allied in outward appearance to the well known 

 European Epizoanthus Couchii (Johnston), Hadd. and Shackl. Obvious differences 

 occur in the number and form of the capitular denticulations, the Antillean 

 representative having fifteen, sixteen, or twenty-one, truncated at their free edge ; 

 while the older species has twelve or fourteen triangular teeth. The tentacles 

 differ in a corresponding manner. Histological characters indicate further dis- 

 tinctions. It is readily separated from the seven other species examined by the 

 two authors mentioned above, and also from the "Challenger" species. Of 

 American forms it appears to bear a close relation to the incompletely described 

 Episoanthus humilis, Verr. (1869), from Panama. 



Parazoanthus, Haddon and Shackleton, 1891. 



Macrocnemic Zoantkese, with a diffuse endodermal sphincter muscle. The 

 body -wall is incrusted. The ectoderm is continuous. Encircling sinus as well as 

 ectodermal canals, lacunas, and cell-islets in the mesoglcea. Dioecious. Polyps 

 connected by thin coenenchyme. 



This genus, with the above definition, was established by Haddon and 

 Shackleton (1891, p. 653), to include macrocnemic Zoanthese with a diffuse endo- 

 dermal muscle, forms which previously had been referred by Hertwig and 

 Erdmann (1888, p. 35) to the genus Palythoa. The authors recognize five species 

 examined by them, and two described by Hertwig and Erdmann. The combi- 

 nation of anatomical characters renders it a well-defined genus. 



Carlgren (1895) has shown that the genus Gerardta, Lac.-Duth., formerly in- 

 cluded, with some hesitation, amongst the Antipatharia, is closely allied to the 

 present genus, differing only in the presence of a strongly developed horny 



skeleton. 



312 



