30 GILBERT 0. BOURNE. 



These peculiar modifications are shown in fig. 8. The histo- 

 logical details have been greatly simplified, but the outlines 

 are correctly drawn with a camera lucida. The reticular endo- 

 derm en' , is seen filling up all the spaces corresponding to 

 the ccelenteron. The stomodseal canals are shown at st. c. 

 These canals are lined throughout by an epithelium exactly 

 resembliug that of the ectoderm on the free surfaces of the 

 body, but staining rather more deeply in borax carmine. 

 Great numbers of nematocysts are embedded in this epi- 

 thelium, and may be seen in all stages of development. Fig. 

 9 is an unripe nematocyst, and corresponds with the stages 

 drawn by Mobius in his account of the development of these 

 structures. (Mobius, ' Ueber den Bau, den Mechanismus und 

 die Entwickelung der Nesselkapseln/ Hamburg, 1866, Taf. ii, 

 figs. 22 and 23). The ripe nematocyst, with its axial body 

 ejected, is shown in fig. 10, and in fig. 11 it is drawn with the 

 thread ejected, but not the axial body. The thread bears a 

 peculiar armature at its extremity. The stomodseum below 

 the mouth is a simple tube, but at a short distance lower it is 

 produced into a number of horns running out towards the 

 attachments of the mesenteries; at a lower level these horns 

 are seen to have anastomosed with one another in such a 

 manner that the stomodseum is converted into a highly com- 

 plicated system of canals occupying the centre of the calyx. 

 This is shown in section in fig. 8. At a lower level the stomo- 

 da3um again becomes more simple, and finally ends in a simple, 

 much compressed tube with a narrow lumen. I was unable to 

 determine to my satisfaction whether the stomodeeum opens 

 below into the axial cavity, or whether it is completely closed. 

 I am inclined to think that it opens by a very narrow passage. 

 As the stomodseum reaches nearly to the bottom of the polyp 

 cavity, the axial cavity below it is very small, and such as it is, 

 it is entirely filled up with mesenterial filaments. The stomo- 

 dseal canals contained numerous fragments of vegetable matter, 

 apparently pieces of leaves. The presence of vegetable food in 

 these canals is interesting, firstly, because I believe it is the 

 ouly recorded instance of a coral feeding on a vegetable diet ; 



