on the Genus Coereba. 497 



that closely-allied species of the vegetable world may live 

 under very different climatic conditions), yet these con- 

 stantly recurring cold snaps in winter might be enough to 

 explain the absence of the genus. 



Failing climatic conditions as an explanation, we may 

 look to the absence of species of the genus from Yucatan 

 and British Honduras as a possible clue. The physical 

 conditions in these two countries are all against the existence 

 of any representative species. In British Honduras there 

 is only a very narrow belt of fertile country between the 

 wide coastal fringe of maugrove-swamps and the arid 

 hills inland, which are covered with " pine " forests ; while 

 as regards the peninsula of Yucatan, the conditions are 

 still more hostile. The country is very flat, very dry, and 

 very hot. The streams run for the most part under- 

 ground, and the only surface-water is found in peculiar 

 natural wells (cenotes). In consequence the Flora, generally 

 speaking, is of a scrubby order, and in winter many of the 

 trees and bushes assume a much faded and withered condition 

 or entirely lose their leaves — conditions which are adverse 

 to the maintenance of a bird that lives chiefly on insects 

 which frequent the honey-laden flowers of j)lants and 

 bushes. 



Yucatan is, in fact, little more to-day than a very recently 

 upraised coral platform, consisting of weathered coral lime- 

 stone of a very rough and pitted nature or, in other places, 

 of sheets of a recent shell conglomerate. 



These facts, as we have hinted, may furnish the clue to 

 the absence of Qrreba from Cuba. For we may conclude 

 that while these Pliocene and Pleistocene coral formations 

 and conglomerates were being laid down beneath the sea, 

 Cuba vTas very much more isolated than it is now. Indeed, 

 it was not only further isolated from Central America, but 

 also from Northern America by reason of the fact that at 

 some part of these periods Florida was likewise in a state 

 of submergence. 



Consequently, if during one of the latest periods of West 

 Indian elevation in either Pliocene or Pleistocene times 



