MUSEUM OF COMPAKATIVE ZOOLOGY. 147 



year. An inspection of the western face of the Miami Reef leaves in 

 my mind no doubt that the process of solution is rapidly extending 

 the general plane of the Everglades to the eastward. On the floor of 

 the more level and lower lying country which constitutes the eastern 

 margin of the Everglade district, we find a similar deposit of limy 

 matter, whicli has been laid down during the process of evaporation 

 of the swamp waters. At the distance of half a mile from the face of 

 the Miami Eeef, this layer was very much thinner than on the lower 

 portions of the reef itself. In the Everglade district the amount of 

 decavino- ve2:etable matter is srreat, and there can be no doubt that 

 running waters of this region become heavily charged with carbon di- 

 oxide, and are thus enabled to dissolve the limy matter with which 

 they come in contact. In the rainy season, as before remarked, these 

 waters rise to the height of from five to eight feet above their level 

 during the dry season, when I observed the district. As the waters ol 

 this swamp rise, they doubtless take a large quantity of the lime into 

 solution. After the rainy season passes, the water is drained away by 

 the numerous exits to the sea. 



It is a noteworthy fact that Biscayne Bay, which receives through the 

 Miami and other streams discharging from the swamps of the Ever- 

 glades on its floor a vast amount of limestone mud. A portion of this 

 mud is composed of the remains of Foraminifera and other organisms ; 

 but microscopic examination of it shows that a large portion of the mass 

 does not exhibit evidence of having recently been in the organic con- 

 dition. It appears to be lime in the form whicli would be given it by 

 a precipitation from water. The quantity of this mud in the control 

 of the tidal and other currents which sweep through these embayed 

 waters is very remarkable. The volume of the material can best be 

 judged by the conditions exhibited by the deposits of limy matter at 

 the eastward end of the cliannel passing from Biscayne Bay to the sea, 

 at the point known as Caesar's Creek. The calcareous ooze moving out 

 from the Bay of Biscayne at this point is so large in amount, that it 

 forms a distinct delta, digitated at its seaward end in substantially the 

 same manner as the mouth of the Mississippi. It seems clear that this 

 great volume of mud comes from Biscayne Bay, and it would be difficult 

 to explain its origin by any action originating altogether in that basin. 

 I am disposed to believe that the surcharge of lime given to the sea by 

 the efiiueut water of the rivers which drain the Everglades leads to the 

 formation of a portion of this ooze by precipitation. 



However it may be as to the origin of the limestone ooze, so plenti- 



