48 McMURRICH. (VoL. III. 
of the thin mesogloea (PI. IV., Fig. 4). I never observed these 
tubercles to be capable of causing the adhesion of particles of 
sand, etc., although the ectodermal cells covering them seem 
to be somewhat different from those in the intervals, being 
more delicate, resembling somewhat those characteristic of 
verruce. The surface of the elevation is not depressed as in 
verruce, and they differ in this respect from these of H. ver- 
ruculatus, which Klunzinger describes as being provided with 
verrucze situated especially towards the upper part, but often 
extending almost to the base. The ectodermal cells are deli- 
cate, but present no remarkable characteristics. The endoderm 
contains numerous gland cells, and is richly provided with “ yel- 
low cells.” The muscular layer throughout is very weak, and 
there is no trace of a sphincter muscle, unless two or three pro- 
cesses of the mesogloea, widely separated, and similar to those 
which support the ectodermal tubercles, may be considered as 
representing it. 
The margin bears a number of short conical tentacles similar 
to those of Rhodactis. No bunches of tubercles are to be 
observed similar to those of H. verruculatus. The disc, which 
measures I.3 cm. in diameter, is covered towards the periphery 
with rows of short tuberculiform tentacles arranged radially. 
There is considerable irregularity in the length of the various 
rows ; their number is about 36, though it is difficult from my 
specimens to give an exact number. In structure these tenta- 
cles are characterized by the small development of the muscular 
layer, by the total absence of nematocysts as in Rhodactis, and 
especially by the nature of the ectoderm cells of the apex (PI. 
IV., Fig. 5). Over the general surface they present no pecu- 
liarities, but just at the apex, where in preserved specimens 
there is a translucent circular spot, the cells become exceedingly 
delicate and closely packed together, so as to resemble very 
closely in general appearance what has been previously described 
for the verruce of Az/actinia. The mesogloea of the tentacles 
and disc, like that elsewhere in the body, is very thin. The 
central portion of the disc is bare, and from it the peristome 
rises up somewhat abruptly, so that the mouth is some distance 
above the surface of the disc. The mouth is almost circular, 
and the gonidial angles cannot be distinguished. The walls of 
the stomodzeum are raised into folds as in Rhodactts. 
