664 
THE VOYAGE OF H.M.S. CHALLENGER. 
developed, just like the parent ; lie said the crabs went down to the sea occasionally 
to “drink.” 
A Mound Bird ( Megapodius ) is common in Santa Cruz Major Island. The calcareous 
sand amongst the bushes close to the sea shore was scratched and turned over in many 
places by these birds in burying their eggs. The guide dug out half a’ dozen eggs closely 
resembling hen’s eggs in appearance from one of these places. They were buried in the 
clean sand at a depth of 3| or 4 feet, and with no mound over them, or vegetable 
rubbish of any kind. The eggs are thus hatched by the simple warmth of the sand 
received from the sun and retained during the night, just in the same manner as 
turtle’s eggs are hatched, indeed turtle’s eggs are found in precisely similar holes. It 
was midday, and the surface sand was not much hotter than the sand below where the 
eggs lay, which felt, as well as the eggs, distinctly cool to the touch. These birds do not 
therefore, as commonly supposed, hatch their eggs solely by means of the heat derived 
from decayed vegetable matter. 
Alcyonarians (social Polyps distinguished by having eight tentacles) are extraor- 
dinarily abundant about the beach of Santa Cruz Major. The reef rocks are covered with 
the soft spongy forms, which form extensive beds, soft and boggy to tread on in wading. 
Amongst these grows a stony coral which is likewise, as was discovered by Mr. Moseley 
on examining its minute structure, Alcyonarian, forming thick erect plate-like masses of 
a chocolate colour when living. The coral is remarkable because its hard calcareous 
skeleton is of a bright blue colour instead of white, as is usually the case, and is hence 
named Heliopora ccerulea. It is, as far as is known, the only surviving representative 
of a large number of extinct forms of Palaeozoic age, which are familiar in the 
fossil condition, and is nearly allied to the well known red coral of commerce. 1 Again, 
another interesting Alcyonarian is abundant, together with those just described, namely, 
the red Organpipe Coral (Tubipora musica). There were cartloads of this coral, dead 
and dried, lying on the beach, which was entirely composed of various coral debris. The 
■Organpipe Coral was not to be found living in shallow water on the reefs, but living 
specimens were dredged from a depth of 10 fathoms. 
The houses of the Moros at Basilan Island have already been referred to ; the town 
was mostly, at the time of the visit, in process of construction by families of Bisayans 
moved from Samboangan, and much of it was being built on causeways and made ground 
constructed with coral rock on tidal mud flats ; some families newly arrived were camped 
on the sites of the houses they were building. 
Separated from Basilan Island by a narrow strait is the very small island of Malamaui, 
mostly covered by a dense forest of lofty trees, many of ' which have the curious 
vertically projecting plank-like roots so fully described by Mr. Wallace in Tropical 
1 H. N. Moseley, On the Structure and Relations of the Alcyonarian Heliopora caerulea, &c., Phil. Trans., 
vol. clxvi. pt. i. pp. 91-129, 1876. 
