20 Scientific Proceedings, Royal Dublin Society. 



by two major septa. Cardinal septum as long as tlie rest. Septa more or 

 less concave to cardinal fossula. Minor septa long, each leaning against a 

 major on the side remote from the cardinal fossula. The counter septum 

 thus has two minors leaning against it. 



The tabulae are irregular, often very oblique. This produces the group- 

 ing of septa seen, e.g. in PI. I, fig. 2, and to a less degree in 

 figs, la and 4a. Symmetrical sections are uncommon. The obliquity of 

 the tabulae has no relation to the position of the fossula (cf. PI. I, 

 figs, la and 2). Eejuvenescence was observed in some specimens. 



The youngest section obtained (3'5 mm. diam.) resembles a young 

 Z. omaliusi, except that already there are two minor septa leaning against 

 the counter septum, and of nearly half its length. The other minors are 

 barely indicated. 



Comparisons. — This coral is convergent in septal plan with Cyathaxonia 

 cormi, with which it is associated. 



It bears a strong resemblance to Zaphrentis cassedayi, M.-Ed.,^ but is 

 distinguished therefrom by the absence of spines on the epitheca. 



From Z. delepini, Vau.,^ it is easily separated by the great development 

 of all the minor septa. In other respects there is considerable resemblance. 



It differs from Z. vatighani, Douglas,' in this same way, and also in the 

 following points ; — The fossula is on the convex side, and is bounded by a 

 single septum on each side ; the cardinal septum reaches the centre ; the septa 

 are concave to the fossula. 



JSndophyllum irregulare, sp. nov. (PI. I, figs. 7-9.) 

 M 2, 4 = Ci. 



Description. — Length 55 mm. Growth very irregular. Strong thicken- 

 ings at intervals. 



Transverse section, mature. — Diameter 17 mm. Central area occupied 

 by tabular intersections only. The medial area contains 37 major septa, 

 very unequal in length, sometimes reaching nearly to the centre, some- 

 times reduced to short spikes, not thickened, often flexuous. Cardinal 

 septum doubtfully to be distinguished. Minor septa appear as teeth on the 

 outer wall. Outer area composed of vesicles which may all be large and 

 loose, with tooth-like septal projections on their outer walls ; or may nearly 

 all be interseptal, so that most of the septa reach the outer wall without 



1 H. Milne Edwards, Histoire Naturelle des Coralliaires, 1857-60, PI. G 1, fig 2. 



2 A. Vaughan, Q. J. G. S., vol. Ixxi, 1916 (" Belgian Paper "), p. 34, and PI. iv, figs. 

 3 and 4. 



3 J. A. Douglas, Q. J. G. S., vol. Ixv, 1909, p. 577, and PI. xxvii, fig. 11. 

 A. Vaughan, Q. J. G. S., vol. Ixxi, 1915 (" Belgian Paper "), p. 35, and PI. iv, fig 7*. 



