68 MCMURRICH. [Vou. III. 
thick, but is of smaller extent than the upper surface of the 
colony ; in consequence of this the polyps towards the periph- 
ery of the colony approach more or less a horizontal posi- 
tion. 
The ectoderm of the polyps is protected by a cuticle, and 
consists of several rows of cells as in Gemmaria isolata and 
the Zoanthus from the Bermudas described by Erdmann. The 
mesoderm is thickly studded with imbedded foreign substances, 
such as grains of sand, foraminiferal and radiolarian shells, and 
sponge spicules, a thin layer only, adjacent to the endoderm, 
being free from these bodies. Neither Hertwig nor Erdmann 
makes any definite statement regarding the arrangement of 
these imbedded particles in their C. tuderculosa, merely stat- 
ing that in its anatomical characters it agrees with the Ber- 
muda form which Hertwig identifies with Quoy and Gaimard’s 
P. lutea. In this the foreign particles are limited to a small 
region of the mesogloea immediately below the ectoderm and to 
the coenenchyma between the polyps, being here scattered ; else- 
where the mesogloea is soft. I was not able to detect in the 
Bahama form any of the definitely shaped calcareous bodies 
with a radiating structure which Miiller and Klunzinger de- 
scribe as occurring in P. tuberculosa and which remind one of 
Alcyonarian spicules.’ The mesogloea, as in other Zoanthide, 
contains numerous endodermal canals and isolated ectodermal 
cell-islands as well as the connective tissue cells. The sphinc- 
ter resembles closely that of Gemmaria, differing from it only 
in that there are a greater number of spaces filled with muscle 
cells towards its upper end. 
The margin of the polyps, as stated above, is tuberculate, the 
tubercles varying in number from 16-18. The tentacles vary 
in number, the largest polyps possessing 36-40 arranged in two 
cycles. The disc is concave, and the peristome elevated and 
provided with minute white tubercles. The stomodzeum resem- 
bled that of Gemmaria in shape. (See Pl. IV., Fig. 20.) 
The mesenteries are arranged on the microtype, and were 
delicate with weak musculature. Unfortunately, the material I 
brought back with me was not preserved sufficiently well to 
allow a study of the histology of the internal parts. I did not 
observe any reproductive organs in the forms examined. Miil- 
ler states that in P. ¢uberculosa the mesenteries unite at the 
