128 Mr. H. M. Bernard on the daughters appear from the sides of larger parent (" apical ") polyps, was described as centrifugal, while that in AnacrO' pora, in whicli an apex of undifferentiated coenenchyma takes the lead and the young polyps appear in it as it grows, was called centripetal. Tiie distinction was thought to be funda-mental. On the other hand, the new genus came very near Monttpora, differing from it chiefly in the fact that the calicles in Montipora are typically immersed, while in Anacropora they bulge up the surfaces of the branches into mounds or eminences. The new genus was accepted at once by Duncan in his revision of Milne-Edwards and Haime's system, and he allied it with Montipora. The ' Challenger ' expedition brought home two new types, which Quelch classed under Ridley's genus, and in 1892 Eehberg * added another specimen and type, bringing the number up to four. The following notes are based upon the study of the specimens and fragments (twenty-two in all) in the National Collection. These include all the existing types except that of Rehberg (^4. s/je/iosa), which is in the Ham-burg Museum. The examination has resulted in the establishment of two new types, one being represented only by fragments, the bulk of the specimens being in the Vienna Museum. Full details will appear in the official catalogue, which is in the press. I was for some time quite uncertain as to the validity of the distinction made by Ridley between Anacropora and Montipora. Slight mounds or elevations on which the calicles opened might and do, indeed, occur in Montipora^ wherever the corallum is very thin, while, on the other hand, we have in Anacropora the streaming axial layer leading the growth, and forming, as in Montipora, the tips of branches, and a further cortical layer formed just as in 3Iontipora. It seemed to me, therefore, that while the fundamental identity in the structure of the colonial skeleton showed that Anacroporcs were really Montipores, the presence of protuberant calicles, which might be a slight return to primitive conditions, hardly justified the establishing of a new genus. Comparison with other types and with the undescribed material in the collec-tion has, however, revealed other characters which are important enough to warrant our retaining the genus, but uniting it with Montipora under a subfamily Montiporinee. "W'hile, then, the fundamental identity in the structure of the coenenchyma shows that Anacropora has branched off * Abh. Nat. Ver. Hamb. xii. p. 46.