

A STUDY OF THE VARIATION AND ZOOGEOGRAPHY OF 



LIGUUS IN FLORIDA. 



By Henry A. Pilsbry, Sc.D. 



CONTENTS. 



I. Introduction 429 



II. Relationships of Liguus and its Advent in Florida 430 



III. Pure and Hybrid Colonies of Liguus 432 



IV. Colors and Patterns 436 



V. Distribution and Migrations of Liguus 438 



VI. Station and Habits 443 



VII. Descriptions of the Individual Colonies 444 



1. Pure Colonies of Liguus crenatus 444 



2. Pure Colonies of Liguus fasciatus roseatus, West Coast 448 



3. Pure Colonies of Liguus fasciatus roseatus, Keys north of Largo 450 



4. Hybrid Colonies of roseatus Xcastaneozonatus, West Coast 452 



4. Hybrid Colonies segregating into roseatus, castaneozonatus and crenatus, Cape Sable 



and South-Central Keys 454 



5. Hybrid Colonies composed of roseatus, castaneozonatus and crenatus, segregating into 



three or four patterns 456 



6. Race of Lignum Vitae Key 461 



7. Race of the Southwestern Keys 462 



VIII. Field-Notes of Mr. Clarence B. Moore 465 



I. INTRODUCTION. 



Students of mollusks, as of many other animals and plants, have often to 

 deal with species, or groups of closely related species, showing a very wide 

 diversity in color and pattern. While in the majority of molluscan species the 

 color and pattern are constant within moderately narrow limits of variation, 

 there are also many species in which great variation occurs among individuals 

 of a single colony. The species of Oliva and Umbonium among marine, and Liguus, 

 Partula, Achatinella and Amphidromus among land snails are conspicuous 



examples. 



Little has been done by conchologists towards the interpretation of "variable" 

 races. No distinction has been made between the omnipresent "fluctuating 

 variations' ' of relatively stable forms and the striking diverse patterns of the 

 others. Experimental work along Mendelian lines with plants in the last few 

 years has shown that a "variable species" is usually composite, several races or 

 "elementary species" living in hybrid colonies. I do not know that any such 

 experimental demonstration has been made in the case of animals except upon 

 domesticated or semi-domesticated forms. The facts brought out by a study 

 of the Floridan forms of Liguus amount to a demonstration that the variable 

 colonies are composite. They are Mendelian mixtures of races found pure in 

 other colonies. Mendel's law of segregation and the doctrine of unit characters 

 in inheritance give a key to the composition of these hybrid colonies. There 

 remain many points which can be elucidated only by breeding the snails. 



429 





