170 THE VOYAGE OF H.M.S. CHALLENGER. 
species of the genus at present known is the typical species Anacropora forbesi, Ridley, 
which was obtained at the Keeling Islands by Mr. H. O. Forbes. 
1. Anacropora gracilis, n. sp. (Pl. X. figs. 6-6ce). 
Corallum small, fruticose, much branched, very porous throughout, light and 
fragile. Branches very coalescent, of nearly equal size throughout, about 4 mm. thick, 
often less, regularly dichotomous, with a widely opened angle, sometimes divaricate ; 
branchlets of nearly the same thickness as the branches, short, rounded at the ends, and 
very easily broken away. Calicles very delicate and much raised, about 1 mm. high, 
subseriate, about 2°5 mm. apart, often much less, round and open nariform, slightly 
swollen, about 1°25 mm. wide, with a comparatively large aperture. Septa twelve, unequal, 
two of the primaries rather large. Coenenchyma extremely loose and porous throughout ; 
surface very finely, closely, and strongly echinulate, especially on the edge of the calicles, 
harsh to the touch. 
This isa much more delicate and fragile species than Anacropora forbesi, Ridley. 
It is smaller and thinner throughout, much more coalescent, with a much harsher and 
more finely spinulose surface; it is strikingly porous and is destitute of any superficial 
layer of dense tissue. The calicles are very easily abraded by the touch, and will 
generally be found to be very shghtly prominent on that account in specimens which 
have been much handled. The clump is about 6 em. high, and rather more in width. 
Locality.— Banda. 
2. Anacropora solida, n. sp. (Pl. X. figs. 77a). 
Corallum arborescent and shghtly ramose, dense, not fragile. Branches originating 
irregularly at an open angle, sometimes divaricate, somewhat elongated, from about 6 to 
7 mm. thick; branchlets thinner, strong, tapering, subacute, rather long, sometimes 
nearly 2 cm. in length. Calicles very small, slightly raised, round nariform, seriate or 
subseriate, about 2°5 mm. apart. Septa twelve, six larger and subequal, six very small 
and sometimes rudimentary. Ccenenchyma very dense and solid, becoming slightly 
reticulate in the internal portion of the apical parts of the branches and branchlets 
surface finely echinulate or granulated. 
This species, though having much of the habit and size of Anacropora forbesi, Ridley, 
is very distinct in the nature of its coenenchyma, which is dense and firm, rendering the 
corallum heavy. The calicles are also smaller and less raised, and the septa less 
developed. Only two fragments of this species were obtained. 
Locality.—Kandavu. 
