6 
on the wall. The interspaces are equal to the costæ in breadth 
and are regularly crossed by thin transverse bars, which give the 
coralum the fenestrated appearance characteristic of T'remato- 
trochi. The wall is stout, and from a dissected specimen I 
conclude that it is not really perforate, the pore-like cavities 
being confined to the external portion of the theca. The wall of 
the recent coral is thus constructed on the same plan as T. 
Kitsoni and T. declivis, fossil species of the genus. 
The dimensions of the type are—Height of corallum, 7:5 mm. ; 
length of calice, 6 mm. ; breadth of calice, 3 mm. Another 
example is of equal size, but the rest are smaller. The majority 
of the specimens are much worn, and were, no doubt, dead corals 
when collected. They were dredged in St. Vincent Gulf and 
Backstairs Passage at depths ranging from 15 to 22 fathoms. 
Genus DenrocYaTHUs, Milne Edwards and Haime. 
Deltocyathus Vincentinus, spec. nov. Pl. ii., figs. la, b, c. 
The corallum is discoid when young and with age becomes 
shortly cylindrical. The under surface is horizontal or slightly 
concave, and there is sometimes a small central protuberance. 
Traces of adherence are common in young examples, and one or 
two are still attached by the entire base. Quite rarely is there 
any scar of former attachment on the base of older corals, The 
wall is perpendicular, or nearly so. 
The calice is circular in outline and flat rather than convex 
from its margin to the abruptly sunken central fossa. The septa 
are in six systems with four cycles. They have sharply serrated 
edges, and their sides are marked by parallel rows of pointed 
granules perpendicularly arranged. They vary in size from the 
long, stout primaries to the short and comparatively slender 
quaternaries. The primaries only are free and the rest form six 
deltoid combinations. All are exsert and rise in arched crests, 
which differ in height according to order. At the central fossa 
the primaries extend both inwards and upwards beyond the more 
gradually arched secondaries and tertiaries. The latter are 
doubly curved and unite before the enclosed secondary in the 
manner characteristic of Deltocyathus. The quaternaries bend 
towards and then join the tertiaries about half-way from the 
margin. The junction of the septa is barely noticeable in perfect 
examples, like the fine one figured, but when the upper surface 
becomes worn, as in dead corals, their union is plainly seen. 
Conspicuous lobed pali are placed before the primary and 
secondary septa, and are connected with them by sunken 
processes; their central ends are fused with the columella. The 
latter is solid below and superficially either papillary or trabecular, 
