California Code, Civil Code - CIV § 2176

A passenger, consignor, or consignee, by accepting a ticket, bill of lading, or written contract for carriage, with a knowledge of its terms, assents to the rate of hire, the time, place, and manner of delivery therein stated;  and also to the limitation stated therein upon the amount of the carrier's liability in case property carried in packages, trunks, or boxes, is lost or injured, when the value of such property is not named;  and also to the limitation stated therein to the carrier's liability for loss or injury to live animals carried.  But his assent to any other modification of the carrier's obligations contained in such instrument can be manifested only by his signature to the same.