1902.] NATURAL SCIENCES OF PHILADELPHIA. 745 



merits of raise. It is believed that the floor of the bay is rising 

 to-day, as it is only by constant dredging thai it is possible for 

 vessels of moderate draught to come to the dock, many of the 

 larger steamers having to discharge their cai'goes in the bay. It is 

 said that formerly any vessel could dock without difficulty. 



The coral rock of the seashore is being carved into huge sea 

 caves, one of the most prominent being under the old Morro Castle 

 at the entrance to the harbor. Further up the coast are two large 



Stalactite sliowing cu]> metliod of growth. 



caves, or rather, a series of caves, that are now above tide and a 

 considerable distance inland. They are known as Cuevas de 

 Caribiss, and are within a few miles of the bay of Aserradero, 

 where lies the wreck of the " Viscaya," adjacent to a cocoanut 

 grove, a few huts of fishermen and charcoal burners and the ruins 

 of a diminutive Spanish fort. The caves were evidently originally 

 carved out by sea action, just as the one under INIorro is being 

 formed to day. They present another proof of the raise of this 

 coast. They are now tenanted by millions of cave bats, Artiheus 



