44 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 13 



depth, it appears that the two land masses were continuous at times in 

 the geologic past. If this is true, the floras of the two mountains should 

 show much in common and a comparison would contribute evidence for 

 the historical problem. Unfortunately, the flora of Sierra Vizcaino is 

 quite unknown, except b}' what may be inferred from neighboring locali- 

 ties of collections, the nearest being northwest of the mountains on San 

 Bartolome Bay, or, as it is now commonly known, Tortuga Bay. Three 

 collecting parties have visited this locality: Hinds on H.IVI.S. Sulphur 

 in 1839, Pond on the U.S. ship Ranger in 1889, and Brandegee on the 

 Wahlberg in 1897. The latter on his spring visit found, "the region was 

 perfectly dry and seemed not to have been rained upon for years. A few 

 plants w^ere recognized that w^re before known only from Cedros Island, 

 and made it evident that an accurate knowledge of the distribution of 

 neighboring island forms cannot be obtained without a more thorough 

 examination of the adjacent mainland." The isolated position of Sierra 

 Vizcaino, sitting out by itself across a broad low desert plain about 60 

 miles wide, indicates that it too was for indeterminant periods in the past 

 an insular body and that like Cedros it may possess its own relic biotic 

 elements. 



There are no meteorological data for Cedros Island nor for the 

 adjacent peninsula. Rainfall is probably under 8 inches annually on the 

 average for the lower slopes and most of the island area, something over 

 that for the highlands. The rainfall incidence is irregular, judging from 

 oral accounts of peninsular natives, and years may pass w^ithout effective 

 precipitation. There is apparently only one source of rainfall and that 

 is in the cyclonic winter storms of the northern latitudes which occasion- 

 ally extend to Cedros. According to the natives, the convectional sumi- 

 mer storms rarely reach Cedros Island. The moist westerlies are reported 

 by the inhabitants of the adjacent peninsula to be the dominant and 

 persistent winds. A fog desert similar to that found along the western 

 border of the peninsula may exist over some of the island. Visitors re- 

 port that fog drips from the trees in the higher elevations to such an 

 extent that it causes little rivulets of water and that these have been 

 mistaken for springs. 



Few botanists appear to have visited the western margin of Cedros 

 and very little has been published regarding its plant life. According to 

 accounts left us by visitors, most of the island is covered w^ith a dis- 

 persed formation of Desert Shrub. Suftrutescents in Eriogonum, Fran- 



