108 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



everywhere in the Bahamas, that the coral heads flourish hest. The ring 

 of coral heads is generally from one hundred and fifty to four hundred 

 yards wide, except at the eastern face, where the width of the reef is 

 nearly a mile and a quarter. 



There is of course nothing to show that the substructure of Hogsty 

 Reef differs in any way from that of the other banks of the Bahamas. 

 It is fair to assume that, like them, it was built up of seolian rocks which 

 have gradually been woi'n away by the action of the sea, so that between 

 erosion and subsidence nothing has been left to indicate the existence of 

 the former Hogsty land beyond the growth of corals which now flourishes 

 upon the underlying seolian strata, and which they completely cover. 



That the corals grow in a moi*e or less circular belt I have attempted 

 to explain by the action of the breakers pounding upon the surface of the 

 bank, thus forming a gigantic pot-hole. Finally the water breaks through 

 this pot-hole on its lee side, forms an opening, and changes it into a 

 lagoon. This explanation of the formation of Hogsty Reef had occurred 

 to me before I had seen the so called Serpulce Reefs of the Bermudas, of 

 the structure and mode of formation of which I gave a short account in 

 the June number of the American Journal of Science for 1894. I shall 

 in my report on the Bermudas further consider this subject. 



THE COAST OF CUBA. 



Plates I., XIII., XIV.. XLI. to XIAII. 



We were fortunate enough, both in going to Santiago de Cuba and in 

 leaving it for Hogsty Reef, to run along the south shore of Cuba, to and 

 from Cape Maysi, in daylight. This gave us an admirable opportunity 

 to obtain an excellent impression of the terraces and the elevated reef 

 extending along that coast, forming so prominent a feature of Cuba at 

 intervals all the way from Cape Cruz to Cape Maysi, and similarly all 

 along the northern coast, past Baracoa, Gibara, Matanzas, Havana, and 

 Mariel. But while we thus obtained an excellent idea of their extent, 

 so superficial an examination could only give me data for the most gen- 

 eral conclusions regarding the part these elevated limestones and the 

 reefs had played in the geological history of Cuba, far less for any views 

 regarding their mode of origin. 



The white honeycombed limestone cliffs which are so characteristic of 

 the whole coast of Cuba are known locally as " soboruco," the name 

 applied by the natives to the honeycombed limestone rock forming the 



