Part II.—Stichodactyline and Zoanthee. 197 
but narrows rapidly beyond. A very short basal canal and several cell-islets 
occur in the expanded portion. The mesenterial endoderm is broad and loaded 
with zooxanthelle ; nematocysts also occur sparingly. 
Male gonads were present in all the numerous polyps sectionized from the one 
colony. ‘The surrounding mesenterial epithelium is enormously thickened and 
the ripe spermaria are enclosed in the very thin mesoglea. Around their 
margin are the deeply-staining sperm mother-cells; filling the greater part of 
the interior are the heads of the ripe spermatozoa, while towards one side are 
ageregated the tails of the spermatozoa (PI. xv., fig. 5). 
One very large, much- ranched colony was trawled from a depth of 10-14 
fathoms on the Pedro Bank, 11th April, 1898, incrusting an aborescent Plumularia, 
as much as 100 cm. high. ‘The ccenenchyme was continuous nearly throughout 
the surface of the Hydroid, only the smallest terminations being free. 
Apparently no Zoanthid at all resembling this form has been described from 
Antillean waters, nor as a member of the nearly related Actiniarian fauna on the 
western coast of Central and South America. 
In habit and external features it compares most closely with Parazoanthus 
dichroicus, Hadd. and Shack. (1891, p. 698), obtained by Prof. Haddon from 
Torres Straits, imerusting a specimen of Plumularia ramsayi. It thus forms 
another instance of the strong relationship, particularly in the Zoanthez, which 
is being established between the Actiniaria of the Australian and Caribbean seas. 
The capitular ridges in P. dichroicus are about eighteen, an increase of two or 
three beyond the number prevailing in P. tunicans. 
I have never observed any dichroic effect given to the alcohol from preserved 
material, a peculiarity emphasized in the specific name of the former. Histo- 
logically important differences are indicated, which leave no doubt as to the 
distinctness of the two species. 
The incrusting particles of sand are siliceous in the older species and calcareous 
in the new; the encircling sinus is filled with dark-brown granular pigment in 
the one, but not in the other. The latter distinction is associated with the 
absence of zooxanthelle in the pigmented form, while they are abundant in 
P. tunicans, which, conversely, is devoid of pigment. ‘The mesenterial musculature 
is less developed in the last-mentioned species. 
External characters alone readily separate it from all other known species 
of Parazoanthus. 
Parazoanthus separatus, n. sp. 
(CAL, Roy ites, ID We IL, Tatoo, ies, eel sahyey sik 245) 
In their retracted condition the isolated polyps present themselves as small, 
TRANS, ROY, DUB. SOC., N.S. VOL. VII., PART VI. 25 
