ART. 20 FLORIDA TREE SNAILS — SIMPSON 11 



juncture of the two latter is a line of hammocks. The entire inner 

 country lies only just above high tide, and whenever during a hurri- 

 cane the wind becomes westerly the water from the Gulf of Mex- 

 ico is driven in to Florida Bay and the region to the north of 

 Sable with great force. As the chain of Florida Keys acts as a 

 barrier against this water passing to the eastward it is dammed 

 up and forced over the south shore, the Sable and southwest coast 

 areas, sometimes covering the highest land to a depth of several feet. 

 Before there w^ere any breaks in this upper chain of islands the 

 dam was almost complete, and doubtless the depth of water became 

 much deeper than at present. As there is a great deal of swamp in 

 this territory, Liguus can not progress from hammock to hammock 

 as they do through the high pine woods for, as I have said, they never 

 crawl over wet mud. There are, however, both Liguus and Oxystyla 

 distributed abundantly throughout this whole area wherever there 

 are suitable hammocks, but they are scattered absolutely hit and 

 miss. At Northwest Cape only capensis is found, while in a little 

 hammock just north of Middle Cape Dr. Edward Mercer and I got 

 loss7nanicus, castaneozoriatus, with hybrids between the two, and a 

 single, fine mamioratus. At Middle and East Capes there is quite 

 a variety of forms, and this is true of the line of hammocks between 

 the prairie and the brackish swamp. In one of these would be found 

 an Oxystyla, in the next perhaps a single form of Liguus^ in a 

 third absolutely nothing, and in the next both Liguus and Oxystyla. 

 Yet in some cases these bits of woods are only a few rods apart. The 

 explanation of this is, I believe, that trees and limbs with snails are 

 torn off by the fury of the hurricanes in this region, probably carried 

 along by the high water and landed on some hammock. One such 

 piece of forest might receive a Liguus, another an Oxystyla, another 

 both, and a fourth none. The ground immediately in front of this 

 row of hammocks is always swampy; that in the rear is wet in the 

 rainy season and dry in the cool part of the year. The snails can 

 not crawl over it in summer, and in winter they are fast to the trees. 

 Some of the cape forms may have arrived during the first elevation, 

 but most came at the second. 



Since the above was written a great highway, the Tamiami Trail, 

 has been opened from Miami west through the Everglades, and at a 

 place on this called Pinecrest, midway across the State and 40 miles 

 from its south end, IMr. Joseph Farnham and Mr. Richard Deckert 

 have found great numbers of Liguus. Many of these are hybrids, but 

 they are generally rather closely related to the forms found on 

 Long Pine Key in the south part of the Glades. It is probable that 

 during one of the late minor subsidences this region was somewhat 

 lower than now and that a strong tidal wave may have carried the 



