154 THE VOYAGE OF H.M.S. CHALLENGER. 
16. Madrepora nasuta, Dana. 
Madrepora nasuta, Dana, Zoophytes, p. 453, pl. xxxiv. fig. 2. 
Two very interesting specimens of this species were collected. In one, the calicles are 
strikingly prominent above, never appressed, quickly obsolescent at a short distance from 
the apex, and almost entirely immersed below so that the aperture is directed more 
outward than upward from the branchlets; in the other, the calicles are less prominent, 
rather appressed, and obsolescent at a greater distance from the apex than in the former 
specimen. In both, many of the branchlets are frequently divided and often proliferous 
above. 
Locality.—Tahiti. 
17. Madrepora effusa, Dana. 
Madrepora effusa, Dana, Zoophytes, p. 455. 
The specimen of this species is a broad, cespitose, and one-sided clump, which has 
spread over dead coral, its growth having evidently taken place under unfavourable 
conditions. As a result of this disturbance the basal disk is very slightly developed, and 
the spreading branches are rather loosely coalescent. The lateral calicles are prominent, 
very irregular in size and shape, being either long or short, compressed-nariform, tubo- 
nariform, or dimidiate. 
Locality.—Amboina. 
18. Madrepora paxilligera, Dana. 
Madrepora paxilligera, Dana, Zoophytes, p. 452, pl. xxxiv. fig. 1. 
A large specimen of this species was obtained. It consists of numerous, closely- 
crowded branchlets arising from a large, solid base, which is nearly flattened below 
and attached by a small pedicel, and from which numerous, closely-placed, very flat- 
tened, coalescent, divided branches spread horizontally. The vertical branchlets often 
arise two or three together, rarely more, and are seldom divided at the apex. The 
lateral calicles are rather large, very crowded, dimidiate or tubo-nariform, a little 
prominent and somewhat appressed ; not immersed below, except at the extreme basal 
parts of the branchlets, but becoming appressed, rounded, somewhat swollen, with the 
aperture opening upwards and distinctly seen from above. 
The species seems to be very close to Madrepora nasuta, and may ultimately have 
to be united with it. 
Locality.—Tahiti. 
