68 THE VOYAGE OF H.M.S. CHALLENGER. 
very compact, except on the apical parts of the upper branches; surface with very 
short and minute spinules, which are rather scattered and wide apart, except on the 
verruce, where they become longer and closer. 
In the apical subpolygonal calicles of this species the tabule can be very easily 
traced. In these cells the septa are but slightly developed, and the tabule originate 
as slight ring-like thickenings within the calicle at some distance from the edge. By 
the concentric growth of this thickening a complete floor is formed which shuts in a 
wide intertabular chamber below. According to the stage of development of the tabula 
the central portion may be pierced by an opening of greater or less extent, which 
gradually lessens and eventually is altogether obliterated when the tabula is complete. 
This species is very distinct from all other known forms, and is represented by a 
rather large specimen, which grew in a more or less horizontal position. 
Locality.—Tahiti. 
9. Pocillopora ligulata, Dana. 
Pocillopora ligulata, Dana, Zoophytes, p. 531, pl. 1. fig. 2. 
Two rather small specimens were collected. They agree in all respects with Dana’s 
excellent figure and description. 
Locality. —Honolulu. 
10. Pocillopora plicata, Dana. 
Pocillopora plicata, Dana, Zoophytes, p. 534, pl. 1. fig. 7. 
The specimens which were referred by Dana to this species have been separated by 
Verrill,! the form from the Sandwich Islands being referred to a new species, Pocillopora 
aspera. Two specimens and some fragments in the collection, which apparently are 
identical with the Pocillopora aspera, agree so closely with the Pocillopora plicata that 
it seems necessary to reunite the two forms under their original name. The outer 
branches of the species are not at all plicate, but are more or less straight, elongated, and 
compressed, 
Locality.—Reefs, Honolulu, at depths of 1 to 2 fathoms. 
11. Pocillopora nobilis, Verrill. 
Pocillopora verrucosa, Dana (non Ellis and Solander), Zoophytes, p. 529, pl. 1. fig. 3. 
3 nobilis, Vervill, Proc. Essex Inst., vol. vi. p. 97. 
Two fine specimens and numerous fragments of the species were obtained. In one 
specimen the branches are often quite thin, though generally broad, while in the other 
1 Proc. Essex Inst., vol. vi. p. 93-96. 
