280 A. FE. Verril—The Bermuda Islands; Coral Reefs. 
Ilyanthopsis longifilis Hertwig. 
Voyage Challenger, Zodlogy, vol. xxvi [p. 13], pl. ii, fig. 2 (gen. and sp. nov.). 
It is a turbinate form, as contracted, with a small pedal disk. It 
had about 160 long, slender, perforated tentacles, in about four rows. 
Wall of column and collar smooth. No acontia; mesenteries 160, 
all fertile and perfect; no sphincter. Height of column, 35™™; diam- 
eter of disk, 70™™; of base, 40™; length of larger tentacles, 40™™, 
It probably belongs to the <Actinide, but in its anatomy it is 
unlike any West Indian species known to me. 
It seems to most resemble Condylactis gigantea. 
Zoanthacea. 
Several species of these social or colonial actinians occur at Ber- 
muda in great abundance, not only on the reefs, but in shallow 
water along the shores, in small bays, and even in tide pools. The 
bottom of Hungry Bay, in the spring of 1900, seemed to be com- 
pletely carpeted with two or three species, over large areas. One 
of the species abundant there was a bright green Zoanthus, another 
was the larger yellow or orange-colored Protopalythoa grandis. Two 
species of Pulythoa occur commonly on the reefs, forming more 
or less extensive pale yellow coriaceous crusts, often several feet 
across. The most abundant is P. mammillosa, in which the polyps, 
when fully contracted, sink entirely into the ceenenchyma, so as to 
show little or no prominences. In this the encrustation of white 
sand is so dense that the colonies can be preserved in the dry state 
so as to retain much of their natural form and size. 
The species of this group are variable in form, color,* number of 
tentacles, etc., and therefore they are difficult to identify, especially 
when preserved. Several recent writers have endeavored to find 
good specific characters in their internal anatomy and _ histology, 
but so far with little success, for the internal structure seems to vary 
quite as much as the external. The mode of growth, crowding, and 
even the state of contraction give rise to apparent structural differ- 
ences, even in a single colony. The mesenteries and tentacles 
* The green, yellow, brown, and olive colors, so common in the Zoanthacea, 
as well as in the coral polyps, are mostly due to microscopic unicellular plants 
(Zoéxanthellz) living symbiotically in the tissues, especially in the cells of the 
endoderm, and varying in relative numbers as well as in color, thus causing 
corresponding variations in the polyps. But they also have, in many cases, 
special pigment granules of different kinds in the ectoderm cells of the disk and 
tentacles. (See p. 210.) 
