304 J. E. Durrpen—Jamaican Actiniaria: Part I.—Zoanthee. 
“in either a linear or incrusting manner.”  Verrill (1869) distinguished the 
genus Mammillifera from Zoanthus ‘‘in haying smaller, shorter, or more sessile 
polyps, and in the tendency to form continuous basal membranes, instead of 
linear stolons.” Hertwig (1882) states that ‘‘ Zoanthus and Epizoanthus are 
distinguished from Mammilifera and Palythoa by the fact that, in the former 
two, the polyps project plainly above the common basis, whilst in the latter two 
they are united up to the free end by basal ccenenchyma.” Andres (1883) 
distributes the various species partly under Polythoa and partly under Zoanthus. 
Hertwig (1888), as a result of the researches of Erdmann (1885), separates 
Mammillifera from Zoanthus by the possession of only a simple mesodermal 
sphincter muscle. M*Murrich (1889) follows Erdmann in this. Haddon and 
Shackleton, however, in their “ Revision of the British Actiniz” (1891), in a foot- 
note to Mammillifera, state :—‘‘ The position of this genus cannot be settled until 
the type species have been recovered and sectionized ”—the types being Lesueur’s 
Mammillifera auricula and M. nymphea. A form, covering considerable areas, 
occurs at Port Henderson and at Drunkenman Cay,* near Kingston, which I 
have no hesitation in identifying as closely allied to the WM. nymphea, of Lesueur, 
and with the better description of the species given by Duchassaing and 
Michelotti for colonies found by them at different islands of the West Indies. 
An anatomical study of this shows that, not only in the fundamental characters 
of the brachycnemic arrangement of the mesenteries and the double mesogleeal 
sphincter muscle, but also in many minuter details of structure, the species agrees 
with other members of the genus Zoanthus as described by Erdmann, M* Murrich, 
and Haddon. Lesueur’s description and figure of J. auricula, the other type 
species, leave no doubt that, when found and examined, it will also have the 
characters of a Zoanthus. 
Since this was first written, Prof. M*Murrich (1896) has obtained from the 
Bahamas an incrusting form which he identifies as Mammillifera nymphea, and has 
shown that it is an undoubted Zoanthus. It is distinct from the Jamaican species 
(p. 345). 
Following Haddon, Me Murrich removes the species placed in his earlier paper 
under Mamumillifera to Isaurus. 
The use of the sphincter muscle, for specific purposes, is well exemplified in 
the genus Zoanthus. Differences are readily seen in the figures of the three 
following species, and these again can be distinguished from the sphincters of 
others represented elsewhere. A marked difference, in the muscle, exists in 
* The Port Royal Cays, known as Gun, Rackum, Drunkenman, Lime, Maiden, South, and South-east 
Cays, are a group of small coral islands outside Kingston Harbour. They are raised but a little above 
sea-level, some with and others without vegetation. The shores and shallow-waters around are the usual 
and most favourable spots for marine collectors. 
