REPORT ON THE DEEP-SEA MADREPORARIA 

 OF THE SIBOGA-EXPEDITION 



BV 



A. ALCOCK, M.B., LL.D., F.R.S. 



Indian Medical Service, corresponding Member of the Zoological Society and Fellow 



of the Geological Society of London. Superintendent of the Indian Museum 



and Professor of Zoology and Comparative Anatomy in the Medical College of Calcutta. 



Sometime Surgeon-Naturalist to the Indian Marine Survey. 



With five pi at es. 



INTRODUCTION. 



YYhen my friend Professor Max Weber suggested that I should deal with the Deep-sea 

 Madreporaria collected by the "Siboga" Expedition in the East Indian Archipelago, I assented 

 readily, because I fancied that the species inhabiting the deep basins of that part of the Oriental 

 Region would be much the same as those found in the depths of the seas of India, to which 

 I have given some study. Had I known, however, that the correspondences between represen- 

 tative collections from the deep-seas of the two regions would amount to less than ten 

 per cent of their sum, I should have been much more diffident as to my qualifications for the 

 proposed task. 



Another unexpected difïïculty, with which I was confronted, was that the "Siboga" 

 collection contained, along with many forms that indisputably belong to the abysses, a large 

 number of other "free" forms — such, e. g\, as the species of Heter ocyathus, Heter opsammia, 

 and Balanophyllia — which, though they have no connexion with the peculiar fauna of the 

 deep sea, yet most emphatically cannot be classed with the reef-forming corals. 



This at once raised the question, which I could have been well content to leave more 

 experienced zoophytologists to discuss, as to where, in the case of Corals, the limits of the 

 deep-sea fauna should be drawn. 



Some writers have avoided this difficulty by including as Deep-sea Madreporaria all 



SIBOGA-EXI'EMTIE XVI ,7. 



,4753 



