2. They are usually divided into two sorts, heriot service, and heriot custom; the former are such as are due upon a special reservation in the grant or lease of lands, and therefore amount to little more than a mere rent; the latter arise upon no special reservation whatsoever, but depend merely upon immemorial usage and custom. These are defined to be a customary tribute of goods and chattels, payable to the lord of the fee, on the decease of the owner of the land. 2 Bl. Com. 422. Vide Com. Dig. Copyhold, K 18; Bac. Ab. h. t.; 2 Saund. lndex, h. t.; 1 Vern. 441.