REPORT ON THE REEF-CORALS. 125 
apex of the projections very sinuous and often discontinuous. Columella well developed, 
rather compressed and tuberculate. 
Two specimens of this species were obtained, the larger of which forms a thin, uneven, 
contorted plate, about 9 em. long and 6 cm. wide, which has grown partly incrusting over 
a dead specimen of the same kind. At the margin it is less than 1 mm. thick, and 
between two of the projections the thickness is scarcely more than 2 or 3 mm. in the 
more central parts. 
Locality. —Tahiti. 
Genus 5. Domoseris, n. gen. 
Corallum compound, consisting of broad, irregularly explanate plates, fixed at the 
centre, and often attached laterally by one or more irregular pedicels, which are especially 
developed in old specimens. The under surface imperforate, very uneven owing to irregular 
depressions, marked with distinct, but fine, costal striations. The upper surface very 
uneven, owing to numerous irregular projections, which correspond to the small depres- 
sions of the under surface; these projections are irregularly scattered and are arranged 
neither in longitudinal crests nor in transverse ridges. The calicles are numerous, scattered, 
developing singly both in the upper angle of the projections and on the extremities and 
sides of the larger ones; the parent calicle nearly or quite indistinguishable. Septo-costee 
very uneven and distinct, continued nearly straight to the margin from adjoining calicles, 
but on the projections on the lower sides of the calicles, and throughout nearly the entire 
portion of the rest of the corallum, and more especially on the older parts, they become 
very irregularly thickened and swollen, shortly discontinuous, twisted, bent and contorted. 
Columella tuberculate, nearly inconspicuous. 
This peculiar genus is well characterised by the nature of the septo-coste, which 
present a decided approach to the structure found in the genus Psammocora. Owing to 
this peculiar structure, the projections are very different from those of the genus Cyllo- 
seris. The presence of the elevated projections, and the nature of the septo-costee separate 
the genus from Leptoseris, which it somewhat resembles at the extreme marginal parts, 
where the projections are less marked and the septo-costze more uniform. 
Three species of the genus are in the collection. 
1. Domoseris porosa, nu. sp. (Pl. V. figs. 4—4c). 
Corallum broad, explanate, thick, being about 15 mm. thick towards the centre, and 
from 5 to 8 mm. at about a distance of 3 cm. from the margin, slightly concave and 
irregularly shallow-vasiform above, chiefly composed of an abundant, trabeculate tissue 
derived from the perforated septa and the crowded synapticule ; fixed below by many 
