MATTHAI— RECENT COLONIAL ASTR^ID^ 33 



III. CLASSIFICATION 



Gemination and Fissiparity. The use of these terms is in a state of great confusion 

 in coral Hterature. Tliis is due to workers on the hard parts trying to set up artificial 

 distinctions between genera and species with regard to the exact mode of multiplication 

 of their corallites. In this way various types of budding have been enumerated, viz., 

 marginal, apical, intra-calicular, stolonal, coenenchymal, etc., all of which can be grouped 

 under two heads, viz., (l) intra-calicinal budding, i.e. budding inside the calyx; and 

 (2) extra-calicinal budding, i.e. budding outside the calyx. The latter is easy to see, 

 while the former can hardly be distinguished from fission. Olgivie admits that intra- 

 calicinal budding appears like fission, but adds that " fissiparity is simply a hastened 

 development of buds under certain conditions and at certain periods of " vegetative 

 growth" in the life of the coral (108, p. Ifi5). 



Duerden recognises the value of the different types of intra-calicinal budding, but 

 distinguishes theni all from fission, by which term he understands complete stomodseal 

 division into two equal or unequal parts (32, p. 513). I have searched in vain among his 

 many figures for one representing a stomodseum in the actual process of division, a phe- 

 nomenon which I have not found in any of my polyps*. Moreover, Duerden maintains 

 that there is a sharp morphological distinction between budding and fission, that in 

 gemmiferous corals the polyps which arise as buds pass through the same stages as those 

 that develop directly from larvse and ultimately possess two directive couples of 

 mesenteries and a cyclical hexameral arrangement of the mesenteries, whereas the 

 products of fission in fissiparous genera have neither the directive couples nor the cyclical 

 arrangement. Exceptions are made in the cases of Porites and Acropora [Madrepora), in 

 which fission does not deprive the polyps of directives nor of the cyclical disposition of the 

 mesenteries. Later the same author uses the term "fissiparous gemmation" to denote 

 occasional cases of fission in gemmiferous genera like Cladocora, Stephanocoenia, and 

 Solenastrea, in which he noticed that the fission products of certain large polyps, 

 possessing more than six couples of mesenteries in each of the two mesenterial cycles, 

 retained the two directive couples and the normal hexameral arrangement. On this 

 phenomenon he remarks : "I conceive that gemmation may occasionally take place at 

 almost any part of the free polypal wall, from the disk as well as from the column- wall ; 

 and, if within the disk, then also around the oral aperture. In this last case the one 

 mouth and stomodseum would be common to the bud and to the parent ; the mesenteries 

 of the one would intermingle with those of the other ; two additional pairs of directives 

 would be developed, as in all other buds ; and the mesenteries as a whole would have the 

 same ordinal and cyclic value as in buds arising on the column-wall. When the bud 

 reaches its full size, it will tend to separate from its parent, and in so doing it will 

 appear as if an enlarged polyp were undergoing fission into equal halves, whereas, strictly 

 speaking, it is the components of the bud-polyp separating from the parent body " (35, 



* On p. 493 Duerden says that he has not actually observed tlae division of the mouth or stomodseum in 

 any of his polyps. 



SECOND SERIES— ZOOLOGY, VOL. XVII. 5 



