30 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



endemics. Dredging produced nearly as many species of Phaeophyceae as 

 were found in the littoral, counting Sargassum driftweed as dredged, for 

 the drifted species generally came from the sublittoral, and less than a 

 sixth of the whole list occurred in both littoral and deep situations. In 

 contrast to the Caribbean area, we have here no truly pelagic Sargassa; 

 considerable beds of Sargassum do occur, rather more often at moderate 

 depths than in very shallow water, and weeds torn loose from these may 

 often drift widely, but do not lose the characters of the attached plant. 



The distribution within the area under survey was also in contrast 

 with that of the Chlorophyceae, exhibiting marked restriction. Of the 13 

 species found on Baja California, only 5 appeared reliably to the south- 

 ward. This is not a fair representation of the Phaeophyceae of Baja 

 Cah'fornia, but it does call attention to the degree in which striking ele- 

 ments of the temperate flora of the Californias end there, for Taonia, 

 Zonaria, Macrocystis, Eisenia arhorea, Cystoseira, and Halidrys were not 

 found to the south of the peninsula and none of the marked types of the 

 southern flora were found so far north except Padina Durvillaei. One 

 should remember that only the southernmost fraction of the peninsula's 

 outer shore is considered to be in the tropical algal zone (Smith 1944). 

 It is very striking how exceedingly few of the plants of the outer side of 

 the peninsula, of the coast to the south of the Gulf, or of the outlying 

 islands appeared in the Gulf itself, altogether only about a half dozen. 

 The Is, Revilla Gigedo showed only a very few (10) Phaeophyceae, of 

 which 2 may be but local, one ranged to the north, and the others have 

 southern or Caribbean affinities. The records from mainland Mexico are 

 too few to signify much ; the relations are a little stronger to the flora of 

 the coast to the south than to the Gulf of California. There are too few 

 data to be useful thence to Ecuador, but for this latitude some suggestions 

 may be ventured on the basis of the Galapagos flora. Twenty-eight species 

 of Phaeophyceae were found in that area, 31 on the other coasts visited, 

 with only 4 in common, a very strange segregation indeed. Of the 28, 

 the presumed endemics number 18, a remarkable proportion, of which 

 but one occurs in the northern Galapagos,^^ 12 in the central Galapagos, 



38 In order to establish a basis for analysis of the Galapagos algal flora an 

 effort was made to define zones within the archipelago. Obviously I. Wenman and 

 I. Culpepper were a distinct northern Galapagos group. It seemed possible that 

 I. Espanola, I. Santa Maria, I. San Cristobal, and the southern part of I. Isabela, 

 with associated small islands, because exposed most directly to currents from the 

 south, might constitute a southern Galapagos group. The balance of the islands 

 were grouped as central Galapagos, but perhaps I. Santa Cruz records should 

 have been assigned to the south Galapagos area, since the collecting there was 

 done on the south coast. 



