32 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



The Rhodophycean flora of the mainland coast and adjacent small 

 islands is subject to less isolation than that of the Is. Revilla Gigedo and 

 Galapagos Is. It is furthermore evident that the aquatic climate is rela- 

 tively uniform ; the coast line under consideration, though long, runs far 

 to the east in the middle portion and is, except for a few Ecuadorean 

 stations, entirely within the north tropic zone. On the whole, the records 

 from any one mainland area are too few to give much evidence, but in 

 general the algal flora of the whole coast line is predominantly tropical. 

 Of the 35 Mexican mainland species about two fifths do not extend 

 farther south, but a half dozen go on to Costa Rica and another half 

 dozen to Ecuador. There are almost as many species here recorded solely 

 from Costa Rica as from Mexico, and surprisingly many from Colombia 

 and Ecuador, considering how little time was spent at work there. The 

 Ecuadorean mainland flora is more related to the flora farther north than 

 to the Peruvian flora southward, as far as the data go. 



The chief collections of these expeditions, within a limited area, were 

 those made about the Galapagos Islands in 1934. These were unequally 

 studied ; the stops at I. Wenman were brief, and I. Culpepper was not 

 visited. Within the central area more thorough work was done, at several 

 stations, and about as much at southern points. 



The relatively small numbers of Rhodophyceae which range beyond 

 the Galapagos archipelago when analyzed as to their most natural rela- 

 tionships seem to show that the southern tier of islands have more species 

 (6) with a southward range than those of the central group (2) and 

 fewer on the tropical mainland (2) against 7 for the central group; 5 

 which occur in both likewise range to the south, and 10 occur on the 

 tropical mainland. Conversely, 6 of the algae of the central islands tend 

 to range to the north against only 3 from the southern tier (barring 3 

 which occur in the Gulf of California), but of the joint floras 13 range 

 to the north. These approximate figures seem to show a greater tendency 

 for the southern islands to resemble the south Pacific flora than do the 

 northern islands, which have more of the flora of the immediate mainland 

 and the coast to the north. 



Rhodophyceae were almost lacking from the I. Wenman collections. 

 Doubtless more extensive collecting would have remedied this lack, but 

 their relative absence does preclude any comparison with other regions. 

 About half of the Galapagos Rhodophyceae came exclusively from the 

 southern tier of islands and about a fourth exclusively from the central 

 area. Inspecting the list for supposed new species, we find about the same 

 ratio. The flora is twice as rich, and twice as rich in novelties, in the 

 lower tier of islands. 



