8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 73 



ceived a fine shell of this form in an exchange from A. G. Wetherby 

 labeled '"''Achatina fasciata, Cuba." I only know of two authentic 

 Floridian specimens of this subspecies, one of which is in the col- 

 lection of the Academy of Natural Sciencies of Philadelphia and 

 was collected by Dr. H. A. Pilsbry on Big Pine Key when on a trip 

 to the Lower Keys with the writer in 1907. The other is a somewhat 

 worn shell, but showing the colors perfectly, that I found on the 

 same island in the village of Big Pine a few years later. D'Orbigny 

 figures a shell in his Atlas which he credits to Cuba and which no 

 doubt came from that island which bears some resemblance to 

 pictus, but it is not that. I found a very similar shell at Luis Lazo 

 in western Cuba that I believe is a hybrid between some form of 

 fasciatus and soUdus. 



It seems a little strange that this snail {pictus) should be reported 

 from Cuba at least three times if it was never found there. I am 

 very much inclined to think that it has actually been collected in 

 that island as well as in Florida and that it crossed the strait and 

 landed on Big Pine Key since the dismemberment of the large 

 island, and so short a time ago that it has not changed any of its 

 characters in the least. There is comparatively deep and open water 

 close up to the big hammock in which both the specimens of pictus 

 were found on this island. 



It is probable that not more than two forms of Liguus ever landed 

 on the great island, although it is nearer to Cuba than any other 

 part of Florida, and it certainly was clothed with hammock at an 

 early date. The reason for this paucity is perhaps the fact that the 

 Lower Keys lie almost directly across the Florida Strait from the 

 western part of Cuba, and the strong eastward-flowing Gulf Stream 

 would naturally carry any drifting material past them. 



No sooner was the great western island, the original of the present 

 Lower Keys, formed than the forces of nature began to destroy it. 

 Every winter several storms called " northers " sweep down from 

 the northwest across the Gulf of Mexico, the wind often blowing to 

 30 or even 50 miles an hour, throwing the water of this ^reat inland 

 sea with tremendous force against the land of this region and cut- 

 ting into it all along its entire northern exposure. As a consequence 

 its northern outline is far more ragged than the southern. Not only 

 this but the water was driven with such force that it was crowded 

 completely through the porous foundation of the island from north- 

 northwest to south southeast so that it came out in strong streams 

 on the south side into the Florida Strait. This water soon formed 

 channels through the loosely compacted rock in the eastern part of 

 the great island, and these were enlarged by scourmg and the action 

 of the carbon dioxide in it. Later the weakened roofs fell in so that 

 open streams reached entirely across, for the most part in exactly the 



