228 CRUISE OF THE BARRERA 



in the one species and wholly different from any 

 other land-shell of western Cuba (its one affinity 

 being in eastern Cuba), we were particularly de- 

 sirous of finding it for anatomical study. An 

 exhaustive search along the base of the high walls 

 of Tumbadero, and far up into its recesses, failed 

 to produce any evidence of its existence. An 

 equally persistent search along the eastern face 

 of Hermanos also gave negative results. 



About the open fields, and especially, perhaps, 

 near the base of the mountains, we noted an abun- 

 dance of the "sensitive plant," — Mimosa pudica. 

 It is a low-growing plant covering with its doubly 

 compound pinnate leaves the ground in patches of 

 several square yards. The "sensitive" quality 

 that gives it its name is displayed in its curious 

 habit of suddenly shrinking when disturbed. 

 This shrinkage gives an impression of a sudden 

 wilting as though the shrub had been scorched. 

 When touched, however lightly, the leaves of the 

 entire plant instantly droop and fold up. The 

 more vigorous the disturbance the wider the area 

 affected. Can this be some highly specialized 

 form of protection against browsing animals that 

 reject dead fodder? This curious contraction of 



