ANATOMY OP MUSSA AND EUPHTLLIA. 21 



On the Anatomy of Mussa and Euphyllia, 

 and the Morphology of the Madreporarian 

 Skeleton. 



By 



G. C. Bourne, B.4., F.I..S., 

 Assistant to the Linacre Professor in the University of Oxford. 



With Plates III and IV. 



The following paper contains a description of the anatomy 

 of two genera of Madreporaria aporosa, Mussa and Eu- 

 phyllia, concluding with a general account of the morphology 

 of the Madreporarian skeleton in the light of the most recent 

 researches on the group. My thanks are due to Professor 

 Moseley, who kindly gave me the specimens of Euphyllia with 

 which I worked, and assisted me with his advice ; to Mr. W. 

 Hatchett Jackson, whom I frequently consulted on the more 

 general morphological questions contained in the latter part of 

 this paper ; and to Dr. G. H. Fowler, who kindly lent me for 

 reference proofs of his latest paper on the Madreporaria before 

 it had appeared in public print. 



Mussa (figs. 1—5 and fig. 17). — For the investigation of 

 this form I had a number of specimens of Mussa corymbosa, 

 collected by me during my visit to Diego Garcia (S. lat. 7° 13', 

 E. long. 72° 23'). These corals grow in large quantities in 

 the more sheltered parts of the lagoon in shallow water. The 

 specimens I collected were covered by three to five feet of water 

 at low spring tides. The colonies are csespitose, the aggregate 

 of the polypes forming what is apparently a very solid mass, 



