This section is from the book "The Law Of Real Property and Other Interests In Land", by Herbert Thorn Dike Tiffany. Also available from Amazon: A Treatise on the Modern Law of Real Property and Other Interests in Land .
We have previously discussed the subject of cross remainders. Similar in their general aspect to cross remainders are cross executory limitations, by which, after the limitation of estates in fee simple to two or more persons, it is provided that, in certain events, the share of each shall pass to the other or others.24 There is one important distinction to be noticed as between such limitations and cross remainders, and that lies in the fact that, even in a will, they are not implied, in so far at least as their existence would involve the divesting of an estate previously vested. In such a case the implication is not necessary to avoid intestacy, as in the case of cross remainders. Thus, when there are limitations to a number of persons in fee, with a limitation over to another person in
22. Doe d. Herbert v. Selby, 2 Barn. & C. 926; Evers v. Challis, 7 H. L. Cas. 531. Thus, in the case of a devise to A for life, and after his death to B if he shall then have attained twenty-one years, hut if B shall not then have attained twenty-one years, then to B, if and when he attains that age, there are alternative gifts to B, one being a remainder and the other an executory devise, and which will ultimately take effect depends on whether B has or has not attained the age of twenty-one at the death of A. White v. Summers (1908) 2 Ch. 256, 266.
23. See White v. Summers (1908) 2 Ch. 258.
24. 2 Jarman, Wills, 1358. See Anderson v. Brown, 84 Md. 261.