168 University of California Publications. [botany 



coast of North America, well marked off, viz.; — the Boreal, 

 the North Temperate, the North Subtropical, and the Tropical 

 Regions. The Tropical Region is almost unknown as regards its 

 algal inhabitants, but from data existing in our collections, 

 seems to have its northern boundary somewhere in the neigh- 

 borhood of Magdalena Bay, on the coast of Lower California in 

 the Republic of Mexico. It may be characterized roiighly by the 

 absence of even the warmer water Laminariacea? and the abun- 

 dance of Sargassacea?, Dictyotacea?, and other tropical groups. 

 From the northern limit of the Tropical Region, there extends 

 northward a Subtropical Region which has its northern bound- 

 ary fairly sharply marked by Point Conception in Santa Barbara 

 County in the State of California. This region is characterized 

 by the presence of Laminariacea? of the warmer waters, such 

 as species of Eisenia, Pelagophyeus, and Egregia (E. lavigata 

 Setchell), by certain Dictyotacea?, as well as warmer water 

 Rhodophyceas, all of which are either strictly limited to the 

 northward by Point Conception, or else are to be found only in 

 warmer isolated areas above it. On passing to the north of 

 Point Conception, a decided change is experienced in the compo- 

 sition of the algal flora. The groups just mentioned are absent, 

 and certain species characteristic of the colder waters to the north 

 are met with, mingled in certain favored and sheltered localities 

 with species of warmer waters. None of the strictly subtropical 

 Laminariacea? are met with, except occasionally the last one 

 mentioned. No Sargassacea? are found, nor any of the Dictyo- 

 tacea?, at least none have been found growing. In turn, we meet 

 with the Nereocystis of the colder waters, with certain species of 

 Laminaria, with the northern Egregia (E. Meitziesii (Turner) 

 Areschoug) , and with other colder water forms, less striking, 

 but no less characteristic of this region. The algal flora of the 

 Temperate Region remains fairly unchanged until we come to 

 Puget Sound, when we find many of its characteristic species 

 intermingled with those of the Boreal Region. The species 

 characteristic of the Boreal Region, extend to some extent, at 

 least, into Puget Sound, intermingling there with the species of the 

 warmer waters to the southward and the latter, in turn, in some 

 special cases, extend even farther northward to the region of 



