STRUCTURE OE A SPECIES OF MILLEPORA. 
133 
B'. Branch of a canal-system which communicates by means of a lateral 
offset with one of the zooid-cavities. 
The dark linear bodies represented as embedded in the calcareous matter 
are cavities bored by parasitic vegetable organisms, the black dots being 
spore-cavities. In one of the calicles a branched mycelial thread is seen to 
cross over between the tubular cavities bored in the corallum. 
Fig. 7 shows the appearance presented under transmitted light by a thin horizontal 
section of the corallum of a species of Millepora from Zamboangan, Philip- 
pines, in which the calicles and canal-systems have become filled with opake 
matter. The black streaks thus shown represent the ramifications of the 
canals of the hydrophyton within the tortuous canals in the substance of the 
corallum, and show their anastomoses with the calicular cavities. 
Fig. 8. Portion of a fine section of the corallum, as seen under Hartnach’s objective 
No. 8, eyepiece No. 3. 
The canals bored by the parasitic fungus are seen traversing the calcareous 
matter. 
At ( a ) the fibro-crystalline elements of the hard tissue project in a series 
of points. 
PLATE 3. 
Fig. 9. View of a group of zooids in the expanded condition. In the centre is the 
short mouth-bearing zooid, provided with only four tentacles. Grouped 
around are seen five mouthless zooids. A sixth such zooid belonging to 
the group is omitted from the drawing for the sake of clearness. 
Fig. 10. Vertical section of the decalcified living superficial layer. A mouthed zooid 
and a mouthless zooid are shown in the retracted condition. In the mouthed 
zooid one tentacle is omitted for the sake of clearness. The open spaces in 
the network of the hydrophyton are in the recent condition occupied by the 
calcareous network. The vessels are in places cut through, and have the pig- 
mented endodermal cells exposed to view. 
E. Superficial layer of the ectoderm. 
Z. Mouthless zooid. 
MZ. Mouthed zooid. 
A. One of the spaces occupied by calcareous matter in the recent con- 
dition. 
B. Secondary branch of one of the canals of the hydrophyton. 
O. One of the cut openings into one of the vessels. 
Fig. 11. View of a group of zooids as seen in the contracted condition. One mouthed 
and three of the surrounding mouthless zooids are shown. The moutlied 
zooid here has five tentacles. The surface of the decalcified coral is here 
mdccclxxvii. u 
