F OR some years I have considered that a re-examination of the generic characters of the Greater Antillean Colubridae might not only give some new insight into the relationships of these snakes, but also throw some additional light on the relations of the islands themselves to the mainland. I have from time to time made a few notes on specimens in the Museum of Comparative Zoology with this idea in view, and recently examined most of the species in the National Museum. I am duly grateful to the authorities of these institutions.