882 Dr. J. E. Duerdcn on the 



LTII. — The Morphology/ of the Madreporaria. — TIT. The 

 Significance of Budding and Fission, l^y J. E. DUERDEJ^, 

 Ph.D., A.R.C.Sc. (Lond.), Bruce Fellow, Johns Hopkins 

 University. 



Vegetative or asexual growth is one of the most prominent 

 characteristics of Madreporarian corals ; yet, however varied 

 in form the colonies produced thereby may become, the 

 methods of polypal increase can apparently be reduced to two 

 sharply defined processes — namely, budding and fission. 

 Much has been written upon the different types of asexual 

 reproduction in corals so far as they can be studied on the 

 skeleton alone, and for systematic purposes an extensive 

 terminology has arisen in connexion therewith. So far as 

 the polyps are concerned, however, the essential morphological 

 distinction between budding and fission has never been 

 established. A study of a large number of West-Indian 

 representatives of both gemmiferous and fissiparous corals 

 reveals that the two groups are characterized by very im- 

 portant differences. Only the essential results and conclusions 

 will be here presented; the full details upon which they 

 are founded will appear in a memoir^ upon the general mor- 

 phology of West-Indian Madreporarian polyps, shortly to be 

 ])ublished. 



The following genera of colonial corals all reproduce 

 asexually by budding from one region or another of the 

 polyi)al wall: — Acropora (Madrepora), Pontes, Astrangiaj 

 Fhyilangia, Cladocora, Orhicella, Solenasfnea, Stephano- 

 caenia Uculina, and Siderastroia. An anatomical examina- 

 tion of numerous decalcified specimens of one or more species 

 of each of the ten genera has been completed, and demon- 

 strates that in every case the individual polyps of a colony 

 are built upon the normal hexactinian cyclical plan. All 

 the polyps possess at least six pairs of primary mesen- 

 teries including two pairs of directives situated at opposite 

 extremities. 



Very different stages in mesenterial development are repre- 

 sented by the mature polyps of the different species. In all, 

 with the exception of Acropora and Porites, the six pairs of 

 primary mesenteries are united with the stomodajum and 

 form a first cycle. In the two genera mentioned only the 

 first four developmental pairs are complete, the fifth and sixth 

 pairs remain permanently free from the stomodreum. Where 

 in other genera additional mesenteries occur the next six 

 nairs are arranged in a cycle alternating with the primary 



