THE NAUTILUS. 21 



found at Chokoloskee, its northernmost limit, Pavillion Key 

 and Seminole Point. 



Now then, what I would like to know is if Capt. Collier 

 brought all these forms of Liguus and Oxystyla from Middle 

 Cape Sable and distributed them in the various localities on 

 the west coast I have mentioned. Forms of most of them 

 have actually been found on the Middle Cape, the Oxystyla, 

 Liguus fasciatus roasatus, L. castaneozonatus, L. crenatus 

 marmoratus, and a couple of other forms of crenatus which it 

 seems he did not bring, or if he did they never became estab- 

 lished. How did it come that the Oxystyla only is found as 

 far north as Chokoloskee, that castaneozonatus is only known 

 from this locality and Babbit Key? Why did he carry mar- 

 moratus to a key four miles from Chokoloskee and not put it 

 on the trees of the latter island why didn 't he take all the 

 forms and plant them on Marco Key ? 



As a matter of fact I have never found any snail on Middle 

 Cape Sable which is really very close to any of these upper 

 west coast forms. The castaneozonatus are a little differently 

 marked ; the marmoratus I have from there is of a different 

 pattern from the Chokoloskee shells and something like a 

 single dead specimen I obtained on Key Vaca. I never found 

 during several visits to the Middle Cape anything that could 

 certainly be referred to lineolatus. While Capt. Collier may 

 have brought tree snails from Middle Cape Sable and planted 

 them on or around Marco, it is doubtless true that several 

 forms of Liguus and the great Oxystyla crossed from the 

 Upper Florida Keys to the southwest coast of the mainland 

 of Florida over a now destroyed land bridge, that this migra- 

 tion was probably made many thousands of years ago and 

 that they reached the Chokoloskee, Marco region after the 

 aborigines had built and abandoned the shell mounds, that 

 they made part of their migrations to the region of their most 

 northern distribution from island to island by water, on the 

 trees they lived on. 



This subject of the geographical distribution of the Liguus 

 and Oxystylas in Florida and the manner in which they 

 migrate will be discussed later in a separate paper. As to the 



