100 Dr. F. Baron Nopcsa on Keruiiia. 



A specimen oi Kerunia in tlic Ijritisli Museum collected by 

 Dr. C. W. Andrews lias the aperture of tlio conical chamber 

 not only constricted but perfectly closcJ up by Hydractiuiaii 

 structure (fig. 10), proving that the outer layer continued 

 growing and developing even after the death of the proble- 

 matical organism that occupied the cavity. In this case, 

 therefore, the Hydractinian growth along the oral opening 

 developed irregularly over the surface of the fossil as charac- 

 terizes a true Hydractinian. 



The study of such an example of irregular growth amply 

 proved by its microscopical structure, both internal and 

 external, leads to the inference that the animal which formed 

 these calcareous masses must have been a Hydractinian. 



(C) Conclusion : Kerunia a Symbiosis. 



There is only one way of merging these two results as set 

 out in the A and B divisions of this paper, and that is by 

 assuming that Kerunia resulted from a remarkably close 

 symbiosis of a Belosepia-WkQ Cephalopod with an encrusting 

 Hydractinian, in which case symbiosis went so far that the 

 Hydractinian overtook the labour of building up the protec- 

 tive shell of the Cephalopod which fixed or controlled to a 

 certain extent the growth of the Hydractinian. 



Only by the death or incapacity of the Cephalopod could the 

 Hydractinian develop in an irregular, and in consequence 

 also an asymmetrical, manner. 



Perhaps the symbiosis of Hydractinians with Pagurus may 

 also throw seme light on these biological questions. 



This explanation of Kerunia is of necessity only a hypo- 

 thesis, and yet it seems more probable than any other theory 

 we can advance, since the phenomenon of symbiosis may be 

 traced among recent Hydractinians, as, for example, H. Icevi- 

 spina, which has the tendency to destroy the Gastropod shell 

 on which it settles. Besides, the symbiosis hypothesis only 

 can account for the otherwise most remarkable fact that 

 among the numberless Kerunias I have examined no two 

 specimens were precisely alike. 



The locality where I found the Kerunias here described 

 and figured was the second low terrace above the temple 

 ruins of Qasr-el-Sagha. The specimens occur in great quan- 

 tities in an oyster-bed [Alectryonia Clat-Beyi, Bellardi) and 

 are always found with their oral openings and the flattened 

 side downwards, so that the dorsal spines and the ends of the 

 somewhat twisted lateral horns are turned upwards as weapons 



