180 
JOURNAL OP THE GEOLOGICAL SOCIETY OF DUBLIN. 
garding these curious islands. Their chief interest appears to be in 
connexion with the observations already made by Darwin on raised 
sea-beaches in Chili and Peru. If I might venture to speculate, these 
beaches are much older than those met with at Callao, as the shells 
met with, subfossils, at the latter place are still to be found recent 
there, and those met with here, though closely approaching the recent 
species, are not absolutely identical. I cannot conclude without re¬ 
turning thanks to Captain John Steevens, of the ship Rienzi, for the 
many facilities he afforded me while making an examination of these 
islands; and also must apologize to the Society for my presumption 
in coming before them with a communication in reference to a science 
(geology) in which I am altogether unlearned,—which fact will be, I 
hope, taken as an excuse for any technical blunders the eyes of the 
initiated may herein detect. 
