Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

422 FOSSIL AND LIVING SHELLS. April subterfuge is, that the various sorts of shells which compose these strata both in the plains and mountains, are the very same with those found in the bay and neighbouring places. Among these shells are three species very remarkable : the first is called ' choros,' already mentioned in our description of Lima ; the second is called ' pies de burros," asses' feet ; and the third ' bulgados,' and these to me seem to preclude all man- ner of doubt that they were originally produced in that sea, from whence they were carried by the waters, and deposited in the places where they are now found. " I have examined these parts with the closest attention, and found no manner of vestige of subterraneous fires. No cal- cinations are to be met with on the surface of the earth, nor among the shells ; which, as I have already observed, are not intermixed with earth ; nor are there stones, or any other hete- rogeneous substances found among them. Some of these shells are entire, others broken, as must naturally happen in such a close compression of them, during so long an interval of time. " The pie de burro has its name from the fish enclosed in it, resembling, when taken out, the foot of an ass. This fish is of a dark brown colour, firm and filaceous ; it is an vmivalve, its mouth almost circular, and its diameter about three inches. The bottom of the shell is concave within, and convex with- out. The colour within is perfectly white, the surface very smooth ; the outside scabrous and full of tubercles. Its thick- ness in every part is about four or five lines; and being large, compact and heavy, it is preferred to all others for making lime. " The bulgados, in the Canaries called bulgaos, are snails, not at all differing in their form from the common, but larger than those of the same name found in gardens, being from two inches to two inches and a-half in diameter. The shell is also very thick, rough on the outside, and of a dark brown colour and, next to the preceding, makes the best lime. " All these species of shell fish are found at the bottom of the sea in four, six, ten, and twelve fathom water. They are caught by drags ; and what is very remarkable is, that no shells, either the same, or that have any resemblance to them, are seen either