484 J. W. Gregory & Jean B. Trench— 
Sryrina, Lamarck, 1816. | 
Stylina macgregort, n.sp. (Pl. XIX, Figs. 1a, 0.) 
Diagnosis.—Corallum massive, with a subplane upper surface. 
Calices irregularly distributed and irregular in shape. They are 
shallow and sunk between broad ribbon-like and apparently solid 
walls, over which the costz were no doubt continued as prominent 
lines. Septa three cycles. The primary septa are much thicker than 
the others and very conspicuous. The hexameral symmetry of the 
septa is usually complete. Both secondary and primary septa join 
the columella; but the secondary septa are much thinner than the 
primary. : 
Dimensions.—Fragment of corallum, length, 60 mm.; width, 30 mm. ; 
corallites, diameter, 4-5 mm. ; calicinal centres, average distance, 8mm. 
Figures.—Pl. XIX, Fig. la, part of the upper surface of the corallum 
(No. 27), magnified 3 diameters; Fig. 1b, part of a polished surface of the 
same specimen, magnified 3 diameters. 
Affintties.—This species, owing to its septal plan, belongs to the 
same group as the type of the genus, S. echinulata, Lam., from the 
Middle Oolite, but its calices are much larger. The most conspicuous 
feature in the species is the prominence of the primary septa, whereby 
it has a striking external resemblance to a Miocene coral from 
Egypt—Stylophora asymmetrica (Gregory, 1898, pl. viii, fig. 4); but 
the transverse section, Pl. XIX, Fig. 1, shows, however, that there is 
no true coenenchyma, and that the coral is one of the Stylinide. The 
species, owing to the conspicuousness and irregularity of the primary 
septa, the continuation of the coste over the thick wall, and the 
thickness of the columella, also remarkably resembles a coral from the 
Pliocene of Java described by Felix (19138, p. 336) as Srderastrea 
micrommata. ‘The transverse section of the coral shown by Felix (ibid., 
fig. 3) seems to us to prove that it is not a Srderastrea, the intimate 
structure of which has been well represented in sections by Dr. Ogilvie 
(1895, p. 181). Felix’s S. mecrommata appears to have the character- 
istics of a true Stylina. It differs, however, from the species collected 
by Sir William Macgregor, since the corallites are more crowded and 
are only from 13 to 2 mm. in diameter. The nearest ally of 
S. macgregort is Stylina tertiaria, Duncan (1880, p. 61, pl. vi, 
figs. 1, 2), from the Khirthar Series of Sind. ‘The two species 
agree by the great length of the coste and the spacing of the 
corallites. But they differ in that S. tertiaria has only two complete 
cycles of septa and as its primary septa lack the unusual thickness of 
its New Guinea ally. 
It is advisable also to compare the coral with S. reuss?, Duncan, 
from the Lower Eocene or Ranikot Series of Sind (Duncan, 1880, 
p. 80, pl. x, fig. 11). But in that species the corallites are smaller, 
being only 2 mm. in diameter ; they are very irregularly spaced and 
have less conspicuous primary septa. S. macgregori of Sind therefore 
agrees better with the Upper Eocene than with the Lower Eocene 
species from Sind. The matrix of this specimen differs from that of 
other corals as it is white and contains open spaces; it may therefore 
come from a different horizon. 
