THE ANATOMY OF THE MADREPORARIA. 409 
Duncania (‘ De Koninck, Nouvelles Recherches sur les animaux 
fossiles du Terrain carbonifére de la Belgique,’ lre partie, 
Bruxelles, 1872, 4to.) is not merely an altered Zaphrentis (cf. 
Lindstrom, loe. cit.). 
Figures and a detailed description of the corallum will be 
found in the works of Lindstrém and Pourtalés already cited. 
MapReEpora, sp. 
For a large quantity of material, taken on the cruise of the 
“Challenger ” from the Papeete reef, I am indebted to Mr. 
John Murray. The species appears to be identical with an 
unnamed specimen in the British Museum labelled ‘ Tahiti, 
10, 8, 69.” The anatomy agrees entirely with that of the 
Madrepora aspera already described (“‘ Anat. Madrep.,” ii) ; 
of the six pairs of mesenteries, those numbered 1, 2, 4, 6, 7, 
9, 11, 12, according to the notation there used, are fully deve- 
loped, while 3, 5, 8, 10 are only attached to the stomodzeum 
for a short distance, and do not develop a filamentar thick- 
ening on the free edge. There are twelve tentacles, of which 
the six entoccelic are longer than the others. 
One polyp, apparently undergoing fission, showed eighteen 
tentacles, not divisible by their length into two sets, and nine 
pairs of mesenteries ; the longer axis of the stomodzeum was 
at right angles to the axial-abaxial plane. The directives 
were not recognisable in this polyp owing to the very slight 
development of the mesenterial muscles; when seen in other 
polyps of this or of other Madreporz they are always in the 
axial-abaxial plane. Observations on the relations of the 
plane of fission to the directives would be extremely instruc- 
tive. 
I have taken this opportunity to figure the typical structure of 
the genus Madrepora (woodcut, p. 410; and Pl. XXVIII, fig. 4). 
GALAXEA ESPERI. 
For a fine specimen of this species I am indebted to my 
friend Dr. S. J. Hickson, who obtained it from the reefs of 
North Celebes. 
