134 LOWER INVERTEBRATES. 



and onions, for which the islands are so justly famous. In some places in the latter 

 islands it is found solidified into a compact red rock in which are found embedded 

 Helices, and other shells belonging to species which are at present alive in Bermuda. 

 The caves of coral islands are sometimes of most beautiful character and of consider- 

 able size. In the Bermudas most of these caves have a submerged floor in which in 

 many cases is sea water which is sensitive to the tides in the neighboring ocean. 

 Caves in coral islands present many very beautiful examples of stalactitic and stalag- 

 mitic formation. Many of the stalactites appear to extend from the cave-roof below 

 the level of tide water, indicating either a wide spread or local sinking of the cave-floor. 

 Of the many beautiful effects of the erosion of the sea water on cliffs of coral rock, 

 one of the most interesting is the formation of natural arches and the like out of sj)urs 

 of the hills projecting into the sea. In the neighborhood of a small Bermudian vil- 

 lage called Tucker's Town there is a very fine natural arch which bears a remote resem- 

 blance to the famous Arco Naturale of the Island of Capri in the Bay of Naples. A 

 similar arch called the "glass window" is found in the Bahamas. 



J. Walter Fewkes. 



