114 
ME. H. N. MOSELEY ON THE 
themselves in fine vertical sections of the polyps of Millepora alcicornis, I think 
I cannot be mistaken in the conclusion that the tentacles of the polyps are 
compound, consisting of a broad central portion provided with five or six short 
pinnae on either side. Such tentacles might well appear as tentacular masses if not 
quite fully expanded*. The tentacles are simply retracted. The layer of cells 
covering their exterior is continuous with that lining the cavity into which they are 
retracted, and ectodermal in character. In vertical sections in Millepora alcicornis the 
stomachs of the polyps are seen to be cylindrical in form, but drawn out and widened 
below by the action of retractor muscular fibres which are attached around their bases. 
The stomach-cavity is lined with very large, inflated, transparent, cylindrical cells. The 
stomach has externally to this a fibrous or muscular wall, which is again covered exter- 
nally, as are the tentacles, by a layer of cells reflected from the wall of the cavity in 
which it is retracted. In transverse sections the stomach has its lining cells sometimes 
so arranged as to show an exactly cruciform central opening between them, the outline 
of the stomach being quadrangular, with the points of the cross directed to the angles, 
in other cases the opening is three-rayed. The retractor muscular fibres attached to 
the stomach are seen, on viewing the organ in horizontal sections from beneath, 
to radiate out from its margin all round, and to be attached to the ccenenchymal 
canals, which, as before described, likewise radiate from the polyp masses. The fibres 
often pass a considerable distance along the canals before they are lost to view. The 
radiating muscular fibres, which are fine and transparent, are gathered here and 
there into bundles, and sometimes appear as if arranged in a regular radiating system. 
Fibres are present radiating at slightly different depths all round the circle. No trace 
of radially disposed mesenteries has been detected in Mille'pora, though fine transverse 
sections have been obtained. No continuous ectodermic layer covering the outer sur- 
face of Millepora has been found ; such must be present, but it has only been observed 
indistinctly in fragments in M. alcicornis , where it is extremely delicate. The specimens 
of both species of Millepora obtained were without generative organs. 
The greenish mass left behind as representing the internal structures of the Zambo- 
angan species of Millepora after decalcification is extremely delicate and transparent. 
It was only observed in the Millepora obtained at Zamboangan, where its green tint 
rendered it conspicuous. The green tint on examination of the mass with a high power 
is found to be caused by a tangle of the filaments of a vegetable organism which bores 
the hard parts of the coral in all directions, and of a slight transparent residue from the 
decalcified corallum. 
Notes on the Structure of Pocillopora, sp. 
A species of Pocillopora, possibly P. acuta-> was obtained at Zamboangan. A pre- 
* July 8, 1876. — Since tlie above was written I have found that these appearances are due to the pre- 
sence in the smaller zooids of large numbers of short knobbed tentacles, which become massed together in 
the retracted condition of the zooid. 
