THE MOLLUSCAN FAMILY PLANORBIDAE 



PART II 



THE PLANORBIDAE INHABITING NORTH AND SOUTH 



AMERICA AND THE WEST INDIES* 



*It was Mr. Baker's plan that Part II should contain full morphological and taxonomic 

 descriptions together with comprehensive illustrations of the shells of all species of the 

 Planorbidae known for North and South America and the West Indies. His voluminous 

 working notes were not near enough objective organization at the time of his death 

 to permit their being edited for publication. Any attempt at preparation of these 

 notes by another hand could not ensure the reflection of Mr. Baker's matured judg- 

 ment and ultimate intent in the casting of specific descriptions, in the portra.yal of 

 indi\idual variability, and in the discussion of geographical distribution and ecological 

 relationships. However, at the time of his death, he had completed fifty-four of the 

 plates intended for this section and had prepared typewritten copy for them. In his 

 desk were found plainly-marked photographic prints of other species sufficient to pre- 

 pare six additional plates and pencil manuscript for descriptions of the figures had 

 been written out. The entire group of sixty plates (82-141) is included as a supplement 

 to Part I, even though the six plates at the end of this series represent working copy 

 in which he might have desired to make some final alterations. For convenience of 

 arrangement and reference, the plates of Parts I and II are presented in a single 

 undivided series at the end of this monograph. 



In addition to the plates for Part II, descriptions ha\'e been prepared for nine new 

 species and seventeen new varieties. 



The foreword was written by Professor Harley Jones Van Cleave, who also 

 assembled and edited the descriptions of the new forms and edited the explanations 

 of the plates.— H.E.C. 



