84 THE VOYAGE OF H.M.S. CHALLENGER. 
2. Lsophyllia fragilis (Dana). 
Mussa fragilis, Dana, Zoophytes, p. 185, pl. viii. fig. 7. 
This species has been referred to the genus Colpophyilia by Milne-Edwards and 
Haime, but it has all the fundamental characters of Jsophyllia, under which it has been 
placed by Verrill,t and it is close to the Isophyllia strigosa on the one hand and the 
Isophyllia cylindrica on the other. 
It is peculiar in the form of the upper parts of the wall, which, in neighbouring cups 
remain distinct as two subparallel lines, the septa passing over and coalescing between 
them. The costze are sublamellate and entire or very finely denticulate. The septa are 
thin, fragile, not perpendicular at the edge, very unequal, and prominent and rather 
distant ; the teeth are long, fine, ragged, and irregular. The columella is generally very 
abundant and loosely trabeculate, and continued from centre to centre. 
A single small specimen was obtained. The form figured as Isophyllia dipsacea in 
the Report on the Florida Reefs, plate vii. fig. 8, seems, from general appearance, to 
be a typical specimen of the species, although the details of the structure of the wall are 
not shown. 
Locality.—Bermuda. 
3. Lsophyllia australis, Milne-Edwards and Haime. 
Isophyllia australis, Milne-Edwards and Haime, Cor., ii. p. 375. 
Of this species, the type of which is in the Paris Museum, two specimens were 
obtained, one of which is much abraded at the centre and on one side, and bears upon it 
a young form consisting of a single calicle, clearly of the same species. The corallum in 
this species is but slightly convex; the costae are decidedly lamellate and delicately 
spinulose, very apparent beneath the rudimentary epitheca; the walls are simple and 
fused throughout ; the septa though strong are thin and close, and the teeth are long and 
generally fine. The number of the septa to the centimetre is very variable according to 
the development of the last cycle, and may be from seven to twelve. 
Locality.—Bermuda. . 
4. Isophyllia dipsacea (Dana). 
Mussa dipsacea, Dana, Zoophytes, p. 184. 
Of this species there are many specimens in the collection. Drawings of the species 
are given in the plates of the Florida Corals,’ but I believe that the specimen figured on 
plate vil. fig. 3, is referable to Isophyllia fragilis, Dana, and not to the present species. 
The specimens obtained can be somewhat approximately arranged in a series, of 
which the extremes are so far removed, that in absence of the intermediate ones, two 
1 Dana, Coral and Coral Islands, p. 328. 2 Mem. Mus, Conup. Zodl., vol. vii. No. 1. 
