FIJI-NEW ZEALAND EXPEDITION 85 
and which contain mesenterial filaments extending considerably 
below the general surface, ova and developing planule quite down 
to the base of the colony. Siphonozoids seem to be absent in this 
species, although very small young polyps are found near the 
bases of the fully grown ones, from which they appear to be bud- 
ded, near the surface of the colony. These could easily be mis- 
taken for siphonozoids, as suggested by Wright and Studer in 
their Report on the Aleyonaria of the Challenger Expedition. 
The only other aleyonarian that calls for mention is the organ- 
pipe coral, or Tubipora, which we saw here in a living condition, 
a new experience for all of us. We preserved some of the smaller 
colonies, showing partly expanded polyps, for subsequent study. 
But this beautiful form has so often been described and figured 
that it need not detain us now. 
Most of the reef corals have been mentioned in the preceding 
chapter. Dr. Vaughan has been good enough to name most of the 
genera represented by our collection of dried specimens. In the 
Challenger Report on the Reef Corals, John J. Quelch enumerates 
sixty species from Fiji, the largest number found in any one 
group of the Pacific Islands, according to these writers. Doubt- 
less others have been added since. 
By far the most conspicuous genus is Acropora which contains 
most of the larger branching forms. Some greatly resemble A. 
alcicornis or the staghorn coral of the West Indies. One very 
beautiful species seems to be the Pacific representative of A. pal- 
mata. It forms a kidney-shaped horizontal plate, usually quite 
symmetrical, about eighteen inches wide. From this plate arise 
numerous closely crowded vertical spikes about three-fourths of 
an inch high, all attaining approximately the same level. The 
upper surface of the colony is slightly concave. Viewed from be- 
low, the corallum is seen to be composed of a mass of anastomos- 
ing branches forming a flabellate structure that appears like a 
solid plate when viewed from above; but below it is a mass of 
branches which anastomose very profusely. The tip of each of 
the vertical spikes is colored a bright bluish pink while the rest 
of the colony is a grayish brown. It grows in the quieter pools 
inside the reefs. There are several species of this wide-spread 
genus. One forms a clump of short, stout branches, the corallite 
walls being unusually thick and the margins incomplete on the 
adaxial side, so that the ends of the corallites look like horseshoes 
