P.R. Laws tit. 31, § 3818
The obligation to deliver the thing sold includes that of placing in the possession of the vendee all that is mentioned in the contract, according to the following rules:
If the sale of real property should be made with a statement of its area, at the rate of a certain price for a unit of measure or number, the vendor shall be obliged to deliver to the vendee, if the latter should require it, all that may have been mentioned in the contract; but should this not be possible, the vendee may choose between a proportional reduction in the price or the rescission of the contract, provided that in the latter case the decrease in the real estate is not less than one-tenth (1/10) of the area given it.
The same shall be done, even when the area appears to be the same, if any part of the real estate is not of the character mentioned in the contract.
The rescission in such case shall only take place at the will of the vendee, when the inferior value of the thing sold exceeds one-tenth (1/10) of the price agreed upon.
History —Civil Code, 1930, § 1358.