332 J. E. Dusrpen—Jamaican Actiniaria : Part I.—Zoanthee. 
ZOANTHEZ (continued). 
MacrocnEMINa&. 
Epizoanthus minutus, n. sp. 
Parazoanthus Swiftii (Duchassaing and Michelotti). 
All the examples having been partially studied in their living condition, and 
generally from an abundant supply of material, it has not been possible in some 
cases to draw up the specific characters in very hard and fast terms. The few 
external features one has to depend upon in the Zoanthide are well known to all 
workers in the group to be very variable; and especially will this be seen to be 
the case in the genera Zoanthus and Palythoa. 
Recognizing the form of the sphincter muscle as of great importance in specific 
identification, I have figured it in all cases. 
Practically all the material has been preserved by simple immersion in a 
four or five per cent. solution of formalin. Owing to the presence of abundant 
incrustations and the great thickness of the mesoglea, the internal tissues of the 
Zoanthidee are rarely well preserved. It is satisfactory to find that, by means of 
formalin, the preservation and histology was, in every case, all that could be 
desired, while, in most, little alteration of form or dimensions occurred; thus 
allowing the number of capitular ridges and tentacles, measurements, etc., to be 
taken at leisure. The colours can likewise be observed for some time, but 
disappear ultimately. 
A curious chromatic change occurred in most of the Palythoa material. The 
colonies, usually cream colour when alive, became strongly brick-red in their 
upper region after immersion for a short time in the formalin. This alteration 
extended also to the ectoderm of the cesophagus and to the mesenterial 
filaments. 
Some importance must be attached to the method of preservation in determining 
the appearance of the various histological characters. With alcohol the mesogloea 
shrinks very considerably. To this disproportionate shrinkage, compared with 
that of the ectoderm and cuticle, is due the contorted or dendriform appearance 
of the outer part of the body-wall often seen in species of Zoanthus. The size 
and appearance of the mesoglceal cavities, especially those containing the sphincter 
muscle, may be much modified. Figs. 1, 2, and 8, on Pl. xvu.a, should be com- 
pared. The last having narrow, almost closed cavities, was drawn from a polyp 
shrunk in alcohol, and the two first from colonies preserved without shrinkage 
in formalin. Specimens of Z. pulchellus preserved later in formalin show open 
cavities like figs. 1 and 2. The figure of the cavities of the sphincter muscle 
of Zoanthus, sp.?, given by Hertwig (1882, pl. xiv., fig. 1), is evidently partly 
determined by this shrinkage. 
