18 PHYSICAL FEATURES ETC. 
REVILLAGIGEDO ISLANDS. 
Neither Salvin nor I were able to visit these islands, and the only information 
respecting the physical features and distribution of the avifauna is from the 
account given by Mr. A. W. Anthony in the ‘ Auk,’ xv. pp. 311-318, after his visit 
in 1897. 
The Reyillagigedo Islands lie to the 8.W. of Cape San Lucas, Lower California, and 
consist of a group of four islands, at some considerable distance apart, but all are of 
volcanic origin and in general appearance extremely rough and broken. Socorro, the 
largest of the group, is about 240 miles south-west of Cape San Lucas and about 285 
miles to the westward of Maria Madre, the largest island in the Tres Marias group, 
off San Blas. It is estimated to be about one hundred square miles in extent, and rises 
to a height of 4000 ft. in the centre, where there is an extinct voleano. ‘The greater 
part of the island is covered with a dense mass of undergrowth which it is almost 
impossible to penetrate, especially on the north and north-west, or weather side. 
‘Trees are abundant there, but do not exceed forty or fifty feet in height, though 
usually covering a considerable area with their spreading branches. On the south 
and east the trees are mostly confined to the cafions, where they are smaller than on 
the northern slope. 
Clarion Island lies approximately about 200 miles westward of Socorro and some- 
what further south, and has little in common with the other islands, either in fauna 
or flora. Its length is about five miles, and width one mile, the ground rising about 
1500 feet above the sea. A few low trees or shrubs, the largest not over ten feet in 
height, are scattered along the main plateau, and in a few places extend to the level 
ground on the south side, which lies between the Mesa and the coast. Nearly the 
whole of this flat ground is covered with a dense growth of cactus (Platopuntia), 
over which has grown a mass of vines, and a passage through this belt can only be 
made by the diligent use of a bush knife. At a short distance from the beach were 
found two small shallow ponds, which contain water during the rainy season only, 
but as the high tides evidently overflow the barriers and flood them with sea 
water, it is doubtful if they are ever otherwise than brackish. At the time of 
Mr. Anthony’s visit, the ponds had been dry for some months, and no water was 
found upon the island. 
As might be expected from the position and vegetation of Clarion, the birds were 
quite different from those on Socorro and San Benedicte. The only land bird common 
to any two islands was the Raven, but on Socorro it was not seen. 
San Benedicte is a small island about three miles in length with an average width 
of half a mile, and lies 35 miles north of Socorro. ‘There is little vegetation, but 
wherever sufficient soil is found, there is a heavy crop of coarse grass growing five or 
six feet in height, and rendering progress extremely difficult. The barbed seeds 
