20 
number in a cycle, and am led to believe that it does not exceed twelve. The 
spines arc confined strictly to the outer or autoporal walls, except in a few of the 
autopores of II. australis, where oue takes its origin from each of the 
transverse or mesoporal walls, as shown by Fischer-Benzon in his II. obliqua, 1 
or by Lambe, both in his figure of II. cateuularius , 2 and that of the var. gracilis > 
Hall. 3 Similarly, I have not seen septal spines in the mesoporcs proper, 
as in Nicholson’s figure 4 of those in ZZ. cateuularius. 
11. False Columella . — No trace of a false columella lias been seen in 
any of the Australian Halysites, although in II. australis the septal spines 
meet at the calicinal centre without coalescing. 
12. Tab nice . — Tabulae are particularly well developed in all three 
forms of zooids throughout the Australian species. As a rule, they are 
complete, and there is but little evidence of vesicular structure, as in some 
exotic forms. For instance, the frequent anastomosis of the autoporal tabulae 
figured by Nicholson in II. cateuularius , Linn., in II. cavernosa , by 
Fischer* Benzon, and more particularly by Steinmann in his conception of 
the first-named species, has not been observed. Not a single instance of the 
highly vesicular nature of the mesoporal tabulae, like that of ZZ. cavernosa, 
F.-B., nor the crowded lenticular vesicles of Lambe’s var. amplitabnlata, 
nor yet the arched tabulae of II. catenularius proper, of the same author, have 
been seen. In nearly all our corals, these diaphragms may be said to be 
distant from one another, and, as a rule, equidistant, but here and there 
occasional patches of close tabulae are met with. They may be on the same 
level in contiguous autopores, or alternate, and mostly horizontal; but 
oblique, concave, bent, or rolling floors, have been noticed. 
The mesoporal tabulae are horizontal and regular, sometimes on the 
same level as those of bounding autopores, at other times alternate 
The gonoporal tabulae are generally similar to those of the mesoporcs. 
As regards their distance apart, they are, as a rule, intermediate between 
those of the other two zooids. Bolling tabulae were observed in 
II. pycnoblastoides. 
1 Fischer-Benzon, Abhamll. Gebeite Naturwis. Verein Hamburg, V, 2 Abth., 1871, pi. ii, f. 5. 
2 Lambe, Contrib. Canadian Pal., IV, Pt. 1, 1899, pi. iii, f. 2 a. 
3 Lambe, Ibid., pi. iii, f. 5a. 
4 Nicholson, Tab. Corals Pal. Period, 1879, pi. xi, f. 1. 
