BARBOUR AND NOBLE: LIZARDS OF THE GENUS AMEIVA. 423 
Although no very satisfactory conclusions, perhaps, can be reached 
regarding the main question of the origin of the species of this genus, 
nevertheless one feature stands out strongly and clearly, and this is 
that the distribution of the Antillean species show by their relationship 
to one another and to the mainland types that they arose from an 
orderly progressive migration, such as would only be possible over a 
continuous area of land, and in no wise display the haphazard char- 
acter which would be the only possible character of a flotsam and 
jetsam fauna. When we remember that the Ameivas of twenty-six 
different islands are already known, this conclusion will in no wise 
surprise those naturalists who know these creatures in their native 
haunts. Quick and active, absolutely terrestrial, they are farthest 
removed in habits from the lizards which we now know are at times 
moved about fortuitously, probably most often by human agency. 
The gekkos which hide in or under the bark of trees, enter and abide 
in human habitations, were from the nature of their secretive ways 
probably a frequent companion of primitive man while upon his 
journeyings. ‘The skinks seem also, probably largely on account of 
‘their very small size, to have been spread far and wide, especially 
in the Pacific Island area, by human agency, and with these resistent 
creatures dispersal by fortuitous flotation probably occurs, but we 
cannot believe that it ever takes place except under the rarest and 
most exceptional cases with even these skinks. With other types, so 
many of which could never be imagined, starting on, surviving, or 
landing from an ocean voyage taken upon a sodden, water-soaked 
natural raft, it is quite useless to argue that the enormous length of 
geologic time makes it possible to say that such flotation may occasion- 
ally occur even using occasionally in a geologic time sense. That so 
many, many types would die invariably were they started forth 
annually or monthly upon a rafting voyage, makes but the more 
Explanation of the Diagram. 
The diagram, page 422, shows the relationship of the different species in the 
genus, the name of each race standing with relation to the others in geographic 
position. Each name occupies a position as near as possible identical with the 
area its habitat would occupy if the whole diagram were superposed upon a 
map of the Antillean region, Central America, and South America, the latter 
somewhat contracted. 
