i8 95 . 



NOTES AND COMMENTS. 369 



was land connection with Central America by way of Jamaica and 

 possibly across the Yucatan Channel, and there was then a con- 

 siderable exchange of species between the two regions. At some 

 time during this elevation there was probably a landway from Cuba 

 across the Bahama Plateau to the Floridian area, over which certain 

 groups of Antillean land-molluscs crossed. At this time it is likely 

 that the more northern isles of the Lesser Antilles, which seem to be 

 volcanoes of later Tertiary and Post Pliocene date, were not yet 

 elevated above the sea or if so they have probably been submerged 

 since. After the period of elevation then followed one of general sub- 

 sidence. During this, the island of Jamaica . . . was first to be 

 isolated, then Cuba, and afterwards Haiti and Puerto Rico were 

 separated. The connection between the Antilles and the main- 

 land was broken, and the Bahama region, if it had been previously 

 elevated above the sea, was submerged ; the subsidence continuing 

 until only the summits of the mountains of the four Greater Antillean 

 Islands remained above water. Then followed another period of 

 elevation, which has lasted no doubt until the present time. . . . 

 The Bahamas . . . have been peopled by forms drifted from 

 Cuba and Haiti. . . . The Lesser Antilles have been peopled for 

 the most part from South America." 



Hanging Foliage. 

 In the latest issue of the Annals of Botany (March), the hanging 

 foliage of certain tropical trees forms the subject of a paper by F. W. 

 Keeble. It is well known that the young leaves and branches of 

 several species of leguminous plants hang vertically downward in 

 the early stages of their life, and the writer has been seeking the 

 causes which have induced this habit. Stahl saw in the occurrence 

 merely a means of protection of the young leaves from the force of the 

 violent tropical rain, which, owing to the stillness of the atmosphere in 

 the tropics, generally falls vertically. From certain experiments of his 

 own he concluded that the pendulous position was not a protection 

 of the tender foliage from the sun's rays, or from too great a loss of 

 water in transpiration. Mr. Keeble, however, found that the alcohol 

 extract from leaves of Amherstia nobilis which had been fixed in a 

 horizontal position, was of a lighter green than that from leaves which 

 hung vertically. Moreover, he found that the delicate miniature 

 leaves of the same plant withered more rapidly than those more fully 

 developed, under similar conditions of exposure. As the older full- 

 grown leaves were also found to transpire much more rapidly than 

 the young hanging leaves, it was inferred that the tougher, more 

 leathery mature organs could bear with impunity a loss far greater than 

 that which sufficed to damage the delicate younger ones. Hence it 

 seems probable that the pendulous position has been assumed, in part 

 at least, as a protection from injury by exposure to direct sunlight 

 and also against excessive loss of water by transpiration ; for the 



