AFFINITIES OF GALAPAGOS SNAILS 309 



their distribution to be of much service in this study, but 

 Dr. Giinther records a woodlouse (Cubaris galapagoensis), 

 which is apparently related to a West Indian form. The genus 

 Cubaris, which is otherwise confined to the West Indies, 

 Florida, Central America, California and South America, is 

 the American representative of Armadillo. The latter has its 

 headquarters in southern Europe. Cubaris, no doubt, owes its 

 presence in America to the fact that some ancestor common 

 to it and the European "Armadillo crossed over by the trans- 

 Atlantic land bridge described in the last chapter. 



On the whole, remarks Dr. Wallace,* the flora agrees with 

 the fauna as indicating a moderately remote origin, great 

 isolation, and changes of conditions affording facilities for 

 the introduction of organisms from various parts of the 

 American coast, and even from the West Indian islands and 

 the Gulf of Mexico. As in the case of the birds, he continues, 

 the several islands differ considerably in their native plants, 

 many species being limited to one or two islands only, while 

 others extend to several. 



A point of great importance in connection with the theory 

 of dispersal of seeds by marine currents is the condition of 

 the coasts of the Galapagos islands. The dried up desert 

 aspect of the islands on landing has been commented upon by 

 Darwin. Dr. Wolff gives us his impression of the same 

 islands during the rainy season. The lower zone up to six 

 hundred feet is only very sparsely covered by vegetation. The 

 whole landscape has a greyish-brown appearance. A Lantana, 

 a couple of Crotons and a few Euphorbiaceae and Compositae 

 are the principal members of this wretched flora. The only 

 plants that thrive in this district are two giant Cactuses, 

 reaching to a height of about twenty feet. They seem to 

 select the driest and roughest spots, where nothing else will 

 grow. Herbaceous plants are restricted in this lower zone 

 to a few parched grasses and a few shrivelled diminutive 

 plants. There are very large districts, moreover, where 

 nothing whatsoever will grow, the ground being paved, as it 

 were, with enormous blocks of lava. At a height of about 



* Wallace, A. E., " Island Life," p. 289. 



t Wolf, Th., " Die Galapagos Inseln," pp. 257260. 



