Eocene Corals, Central New Guinea. 487 
Figures.—Pl. XX, Fig. 16, part of a transverse section of specimen No. 18; 
x 3diam. Fig. la, part of a vertical section of the same specimen, showing 
the horizontal exothecal dissepiments ; x 3 diam. 
Affinities. —This species is represented in the collection by four 
specimens (Nos. 9, 10, 18, 19), in some of which, however, the septal 
structure has been destroyed. Duncan has described a species, 
P. eocenica (1880, p. 66, pl. xix, figs. 8-10), from the Upper Khirthar 
or base of the Nari Series in Sind; it has more numerous septa, 
though the fourth cycle is not complete ; the septa of the third cycle 
are much longer and the corallites larger than in P. macgregort. 
The well-known European Miocene species P. desmoulinsi, 
Ed. & H., 1851, has several resemblances to P. macgregori ; but it 
has a more compact exotheca and its primary pali are smaller than 
the secondary pali. 
The specific name in Heliastrea tabulata, Martin (1880, p. 140, 
pl. xxiv, fig. 21, and pl. xxvi, fig. 4), from Java, suggests comparison 
with this species; but Martin’s illustrations show that his species is 
not a Plesiastrea. 
Kosya, Gregory, 1900. 
Kobya hemicribriformis, n.sp.. (Pl. XXI, Fig. 4.) 
Diagnosis. —Corallum massive ; external shape unknown. Corallites 
very large, closely crowded. Septa in four cycles which are 
generally complete. The primary septa are large and thickened 
with a paliform expansion at the inner end. Similar expansion and 
thickening also occur in some of the secondary septa, which are as 
long as the primary. The columella is large and it occupies a sixth 
of the diameter of the corallite. The alternate septa are usually 
eribriform and appear in sections as rows of isolated trabecule ; but 
in some of the younger corallites, owing apparently to a secondary 
thickening, all the septa may appear solid. 
Dimensions.—Fragment of the corallum, No. 35, length, 70mm.; width, 
5-5 mm. ; thickness, 40mm.; diameter of corallites, 12-14mm.; distance of 
calicinal centres, 12-22 mm. (average 15 mm.). 
Figure.—Pl. XXI, Fig. 4, part of polished surface ; nat. size. 
A finities.—This interesting coral is represented in the collection 
by six specimens (Nos. 30-5). They all appear to have come from 
the same bed, as they are in a light yellow limestone in which the 
matrix is paler in colour than the coral. The generic position of 
this coral is not free from doubt owing to uncertainty in definition 
of two genera. Dr. Andrews collected in the Miocene rocks of 
Christmas Island a small fragment of a coral which was included in 
Coscinareéa, as among the genera then established it was nearest to 
it, and the material was inadequate for the establishment of a new 
genus. The coral from New Guinea probably belongs to the same 
genus. Though the synapticule are scarce, they are quite distinct, 
and there can be no doubt that the coral is a compound fungian in 
which some of the septa are cribriform. The coral resembles the 
Jurassic Aobya, which, as shown by Kobya crassolamellata, Gregory 
(1900, pl. xxiii, fig. 2c), has the same fascicular columella and 
alternation of solid and cribriform septa; but in the Jurassic Kobya 
the trabecular structure of the septa is more regularly developed. 
