Like his novels about the Old West, Larry McMurtry's memoir ''Books'' is an elegy for a disappearing way of life. For McMurtry, selling used books was a calling, one that attracted eccentric personalities (like the store owner who hid his best books in paper sacks) and demanded esoteric knowledge, ''near to alchemy,'' of ''editions, variants, points, bindings, provenance, cost codes.'' McMurtry especially relishes the tactile aspects of the trade most threatened by the Internet. ''What fun is there in clicking,'' he asks, ''compared to the pleasure of handling a fine copy of a rare book?'' Indeed, the state of the art in used-book selling these days seems to be less about connoisseurship than about database management. With the help of software tools, so-called megalisters stock millions of books and sell tens of thousands a week through Amazon, AbeBooks and other online marketplaces. Some sellers don't even own their wares. They just copy other sellers' lists and then buy the books as necessary, pocketing the markup (though none acknowledge the practice, since it is banned on most commercial sites). [ABSTRACT FROM PUBLISHER]