276 CRUISE OF THE BARRERA 



jects upon trees and shrubs, their bright yellow 

 polished surface causing them to appear at a short 

 distance like flowers. Did they not possess some 

 disagreeable quality as food, they certainly could 

 not survive in their present exposed mode of life. 

 Other species of land mollusks inhabiting the same 

 general locality are forced to keep in hiding during 

 the daylight hours to escape the attacks of birds 

 that feed ravenously upon them. The fact that 

 all land mollusks lay eggs profusely would indicate 

 a high mortality from natural enemies. 



Despite the vast quantity of individual speci- 

 mens of land-shells found here, the actual number 

 of species is not great, probably not over twenty 

 or twenty-five inclusive of the minute forms. This 

 might be considered high for an equal area in a 

 northern climate but it can hardly be compared 

 with the astonishing number of species to be en- 

 countered in certain Jamaican localities. In one 

 "cockpit" of an area less than ten acres, two of 

 us had once taken seventy species of land mollusks, 

 and upon another occasion a locality of about an 

 acre near Savanna la Mar in Jamaica netted us 

 the extraordinary total of eighty species. But 

 these shells were of the greatest interest to us. 



