TWO NEW TYPES OF ACTINIARIA. 
145 
the apices of the “ roots ” is generally well supplied with 
nematocysts, that of the finger-like process is simple and 
devoid of nematocysts when present, but in the older specimen 
it has generally disappeared, leaving the mesogloea bare. On 
the latter a slight musculature is generally recognisable, but is 
not sufficiently strongly developed for a determination of its 
origin and direction ; it probably agrees with that of the rest 
of the animal. From the true tentacles these structures are to 
be distinguished by their shape (the presence of the “ roots”), 
by the absence of nematocysts on the motile finger-like 
process, and by the fact that they are irregularly distributed, 
bearing no relation to the mesenterial chambers either in 
number or in position, but appearing in all stages of forma- 
tion in the neighbourhood of a single mesenterial chamber 
(fig. 4). 
The true tentacles are set on the boundary between oral 
disc and stomodaeum. In the largest specimen they were 
twenty in number, i.e. one to every pair of mesenteries, with 
one exception. In the smallest specimen fourteen were present 
as against eleven pairs of mesenteries. They are perfectly 
normal evaginatious of the intra-mesenterial chambers (ento- 
coeles) ; their ectodermal layer is slightly marked off into 
batteries of nematocysts, most obvious in longitudinal sec- 
tions. The ectodermal longitudinal muscle is well developed, 
the endodermal circular layer much weaker. No pore is 
present at the tip of the tentacle. 
The stomodseum, which follows immediately on the ten- 
tacles, in the expanded specimen occupies the usual position, 
but in the contracted examples is turned upwards and inwards 
in the remarkable manner represented in fig. 3, st. It is 
covered by a single layer of deeplv-staining columnar ectodermal 
cells. No siphonoglyphe is recognisable on it at any point, 
in either the expanded or contracted specimens. 
The musculature of the general wall of the body is for the 
most part very slightly developed, but may be recognised as 
consisting of an endodermal concentric (circular) layer, and of 
an ectodermal radial (longitudinal) layer. As Prof. Hertwig has 
