6 allan hancock pacific expeditions vol. 12 



Las Tres Marias^ 



Considerably southwest of I. Isabel lies a small group of high, rocky 

 islands called Las Tres Marias. The Hancock Expedition of 1939 effected 

 a landing on the middle island, L Maria Magdalena. This was done at 

 considerable expenditure of effort and some risk, for there was neither 

 safe anchorage nor suitable landing place about the islands. For the most 

 part their margins are sheer clififs, and even when there is no wind- 

 whipped wave action the regular surges break heavily on their sides. As 

 the surf crashed on the rock faces a few of us, as opportunity offered, 

 leaped to footholds on the cliffs and scrambled up for such collecting as 

 could be accomplished. It was obvious from the skiff that there was a 

 good algal vegetation at depths and under surf conditions which made 

 collecting impossible, and some even in the upper surf zone. However, 

 when we got ashore the writer found that little could be secured. It was 

 not possible to skirt the shore ; all that could be done was to explore the 

 little gully or open crevice in which he had landed. By clambering down 

 the slippery cliffs as the waves receded, a small amount of dwarfed mate- 

 rial could be prized or scraped from the rocks in the upper surf zone in 

 the few moments before the return of the rollers forced a precipitous and 

 uphill retreat. 



At first considered altogether unpromising, the little samples were 

 bottled ; when studied later, they proved to have yielded about ten things, 

 of which a couple were not otherwise secured. Dredging off these islands 

 was even more successful, hauls at depths of 6-22 meters yielding some 

 extremely interesting plants. The most important probably was a new 

 species of Haloplegma, one of the few truly spongy Ceramiaceae of the 

 American flora, a new Bryothamnion, Dasya Stanfordiana previously 

 only known from the Galapagos, and Amphiroa foliacea, a western Pacific 

 species, with other corallines. 



Islas Revilla Gigedo, Colima, Mexico 



Isla Clarion^ 



The Is. Revilla Gigedo lie far offshore from mainland Mexico, being 

 much to the southwest even of the end of Baja California, but they are 

 administratively attached to the province of Colima. The westernmost of 

 the group, I. Clarion, was visited in 1934 and 1939. It lies at a consider- 



6 For description see Fraser 1943b, p. 139. 



6 For description and illustrations see Fraser 1943b, p. 70, pi. 74, fig. 157, pi. 

 75, fig. 159. ' ^ ' ^ ' ^ 



