468 MR. H. N. MOSELEY ON THE STRUCTURE OE THE STYLASTERIDiE. 
which is so remarkably developed in Sporadopora and Allopora, and traces of which 
appear in nearly all the genera, is very remarkable. It gives the soft structures of 
Allopora at first sight, a still closer resemblance in arrangement to that occurring 
in Anthozoans, than does the very curious simulation which exists in its corallum. 
The resemblance is, however, in both instances merely superficial, and of no genetic 
significance. 
The branched and fringed processes of endoderm described as embracing the embryos 
in Errina and Stylaster appear to correspond with the similarly branched structures 
in Cordylophora, lacastris, described and figured by Allman and F. E. Schultz e A 
1 have described them as outgrowths of the spadix, but possibly the cup-shaped 
endodermal structure supporting the ova should not be so designated. 
The endoderm of the Stylasteridse is always coloured, and seems most frequently 
to assume various shades of red or violet colouration, but in A stylus subviridis it is 
green. The corallum itself is in some species coloured, especially, it would appear, in 
Disticliopora, but no doubt in many instances the colouration ascribed to the cal- 
careous structures is in reality due to endoderm dried up within the interstices of the 
corallum. 
In a former paper I conjectured that possibly shallow water Stylasteridse might bear 
free gonophores, and perhaps medusiform ones, and that the occlusion of the gonophores 
within calcareous structures, and their adelocodonic condition, was due to the fact that 
the forms examined lived in the deep sea. This suggestion was in accordance with the 
observations of Allman, who has found fixed sporosacs in all deep-sea Hydroids 
examined by him.t I find, however, from specimens sent me by Count de Poltrtales, 
that ampullae are especially well developed on the shallow water Stylaster roseus ; those 
in the female stocks being very large and prominent. There can, therefore, be little 
doubt that these structures occur throughout the family. 
In all the Stylasteridse in which the gastropores have styles, the gastrozooids must 
be protusible in the expanded condition to a very slight extent. And the fact that in 
some genera the gastrozooids lose their tentacles seems to bear out this supposition. 
No doubt in active life the dactylozooids extend like long and filiform tentacles and 
catch and convey food to the gastrozooid, which nourishes them in return by means 
of its basal canals and the general circulation. It is to be noted that in those genera 
in which the gastrozooids have no tentacles, tentacles are wanting in the entire stock. 
The nariform and tubular projections of Errina are no doubt contrivances for 
extending the reach of the dactylozooids, whilst at the same time protecting them. 
In Acantliopora the bases of the dactylozooids are pushed out to a remarkable dis- 
tance from the gastropore mouths, and subsidiary dactylozooids of a smaller kind 
seem to be necessary to ensure the conveyance of the food to the gastrozooid. 
* F. E. Schultze, Ueber den Bau unci die Entwicklung von Cordylophora lacastris. Leipzig: W. 
Engelmann, 1877, p. 34, plates 3, 4. 
f Allman, “ Gymnoblastic or Tnbularian Hydroids,” Vol. II., p. 155. Nature , Oct. 28, 1875, p. 556. 
