200 Southern Extension of California Flora. [ZOE 
southward into the San Ignacio Lagoon and that running north- 
west into the Pacific. 
It has been shown in Zoe* that the flora of the Cape Region 
shows a greater affinity to that of Sonora than to that of Alta 
California and a preponderance of Mexican forms prevails as far 
north as Calmalli, where the vegetation, on account of the 
disappearance of southern plants and the accession of numerous 
northern ones, assumes a decidedly Californian aspect. Of course 
there is not as great a change as would be caused by the inter- 
vention of a high mountain range or a body of water, but at the 
lower and middle elevations the traveler from the south soon 
perceives a difference in the surrounding vegetation after crossing 
the low divide before reaching Calmalli. 
East and west of this dividing region, higher and as yet 
unexplored mountains extend southward and doubtless carry 
along their summits many Californian plants to a lower 
degree of latitude, and the impossibility of drawing a line 
between the northern and southern floras is further shown by 
the fact of maritime species of the Pacific Coast extending 
their limits southward a greater distance than would be sus- 
pected, especially upon the islands, in the same manner as the 
more southern maritime flora is continued northward to those 
islands off the coast of Alta California. 
There is another locality, equally important concerning the 
southern extension of Californian flora and especially interesting 
in that it must certainly be the most southern habitat of many 
plants. This interesting region is the high mountain known as 
San Pedro Martir, situated about one hundred and twenty-five 
miles southeast from San Diego, and much nearer to the Gulf of 
California than the Pacific Ocean. It is an extensive plateau 
rather than a mountain, having an elevation of seven or eight 
thousand feet and traversed by numerous rocky ridges reaching 
two or three thousand feet higher. It is the highest part of the 
elevated region extending southward from Campo and the Cuya- 
maca Mountains, which here culminates and falls away at the 
south to so low an elevation, that in crossing the Peninsula from 
* Zoe iii, 223. 
