ART. 20 FLORIDA TREE SXAILS SIMPSON ' 19 



carry it aAvay with it, just as they carry away large seeds. The 

 Liffuus when disturbed throw out a quantity of a mucilaginous sub- 

 stance which is very slippery, and in such a case it might easily 

 happen that the snail would slip and fall to the ground during the 

 flight of the bird. If it should fall in a hammock in an uninjured 

 condition there would be nothing to hinder it from making its home 

 there, and if gravid laying its eggs and establishing a colony. Such 

 distribution would be essentially the same as if the snails crawled 

 through the pine forest. 



As the changes of land level and the movements of the Liguiis 

 have been somewhat complicated I will briefly recapitulate. Thest 

 snails in Cuba are closely related to our forms and without a doubt 

 are their ancestors, often scarcely removed varietally. I am sure 

 that the close resemblance of a number of forms from the great island 

 to those of our State are not accidental but that they indicate very 

 close relationship. I have actually seen snails there that are very 

 much like graphieus^ liv'mg-stoni^ viiamiensis, septentrional is, elegans, 

 subcreTiahis, eburneus, castaneozonatus, and Tnosieri, and I have no 

 doubt that there are other contiguous forms. 



Trees in which these Cuban snails grew were washed out, carried 

 with their living loads down the torrents into the sea and swept by 

 current or the force of hurricanes along the Florida Strait; the 

 southeast winds of that region would bear them on to our lower shores 

 where, because of hurricane tidal waves or very high autumn tides, 

 they would be landed high and dry on our shores where they could 

 form colonies. 



There was a great subsidence of Florida during early or mid- 

 Pleistocene time, and the region now occupied by our Lower Keys 

 and the southeastern part of our mainland received a deposit of 

 oolitic limy beds. A long, curving coral reef began to grow along 

 the south and southeast part of the State from near Cape Florida 

 to the south side of Ramrod Key. During the elevation that fol- 

 lowed, the sea swept this oolitic material up along our southeast 

 coast and formed a series of low ridges as the shore retreated and 

 when this land was high enough it became covered with Caribbean 

 pines whose seeds were wind blown from Cuba. A single great 

 island was raised covering the area of the present Lower Keys and 

 seeds from west Cuba, for the most part, were borne in on the Gulf 

 Stream and the large island partly planted with hammock growth. 

 Two large hammocks were formed on what was then the open coast, 

 one at Fort Lauderdale, the other at Miami. 



A gravid snail much like our Liguus solidus grapMcus drifted in 

 from near Cabanas. Cuba, was landed on the lowe^: island and be- 

 came established in the hammock, spreading over the greater part 

 of the area and breaking into several varieties before the land was 



