IN THE STOMODGEUM OF THE ALCYONARIANS. 
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which lies between the attachment of the two ventral mesenteries only, it is marked 
by a distinct thickening of the epithelium, and the cilia are long and strong. 
In the genus Clcivularia, in which the non-retractile polyps stand apart from one 
another on a flat creeping stolon, the siphonoglyphe is marked by a considerable 
thickening of the wall of the stomodgeum, but the cilia are comparatively short and 
delicate. Moreover, the siphonoglyphe does not extend over so great an area as it 
does in Alcyonium, for in a series of transverse sections no trace of it can be found 
in the outer two-thirds, but only in the inner third of the stomodgeum. 
In the genera SpongoJes and Nepthya the siphonoglyphe has about the same area 
and extent that it has in Alcyonium. My specimens of Nepthya are not very well 
preserved, but, although the general histology is not easy to make out, the general 
features of the siphonoglyphe are quite manifest. My specimens of Spongodes are, 
however, beautifully preserved, and in them the cilia which line the general surface 
of the stomodgeum may be easily seen. In most Alcyonaria which have been pre¬ 
served in spirit these cilia are not easy to observe. 
In the genus Briateus a very definite siphonoglyphe is present with long and delicate 
cilia. 
In Tubipora the siphonoglyphe is well marked, and provided with a dense armature 
of long and strong cilia. 
I was fortunate enough to obtain a fine specimen of the rare Ccelogorgia palmosa 
from Zanzibar. This genus, which resembles many of the Gorgonian Alcyonarians in 
the complex branching of its axis, and in the fact that the polyps are not completely 
retractile, differs from them in that there is no axial skeleton, but a single large canal 
runs along the axes of the colony and its branches. In transverse section the cavity of 
the stomodgeum presents the appearance of a short Tj the cross portion of the T being 
the siphonoglyphe (Plate 50, fig. 3). The siphonoglyphe is beset with cilia, which, 
though very much longer than those of the rest of the stomodgeum, are shorter and 
more delicate, comparatively speaking, than those found on the siphonoglyphe of other 
forms. 
Passing on now to those forms which exhibit the phenomenon of dimorphism. 
In the genus Sarcophyton, the dimorphism of which was first pointed out by 
Kolliker (9), and subsequently confirmed by Moseley (14), the autozooids possess a 
siphonoglyphe which is not so well marked as it is in the preceding genera. It is only 
| present along the inner third of the stomodgeum, it never occupies a greater portion of 
I the wall of the stomodgeum than that between the two ventral mesenteries, there is no 
marked thickening of the epithelium of the stomodgeum, and the cilia themselves 
are neither so numerous nor so strong as they are in other cases (Plate 50, fig. 4). In 
the siphonozooids, however, the siphonoglyphe is very well marked; there is a decided 
thickening of the epithelium ; it extends along nearly the whole of the ventral side 
of the stomodgeum, from the mouth to the body-cavity; it extends round the wall 
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