146 



what aclhcsivc (as tli<nit;h not entirely dry). It covers the floor 

 to a depth of from one to six inches, and is evidently the result 

 of protracted deposition. Our first thought, upon examining this 

 material, was of guano, but a further examination of the cave 

 gave no evidence that it was now or ever had been used as a sea- 

 bird habitat. There were no traces of nests, roosting places, or 

 the other customary evidences of a guano cave. 



The irregular ceiling ])roved to be almost entirely covered with 

 a crystalline layer that was obviously still in process of forma- 



