In 1285, Parliament passed the Statute De Donis Conditionalibus, which, in effect, abolished the Fee Simple Conditional and replaced it with the Fee Tail. See casebook at p. 300
The Fee Tail is an estate of potentially infinite duration and of inheritance, however, it is inheritable only by the "heirs of the body" of the grantee, i.e., by the lineal descendants of the original grantee of the Fee Tail.
Notice that the Fee Tail is so called because, as the French word "taille" (to carve, to prune, to trim, to cut down) suggests, it is an estate that is inherited only by certain heirs of the original grantee, that is, by the "heirs of his body."
As Prof. Moynihan explains: "After De Donis, a gift of land "to B and the heirs of his body" created an estate in Fee Tail in B. The estate would last so long as there were any lineal descendants of B living and upon failure of such issue the land would revert to the donor or his heirs....For example, suppose in 1720, O conveys to B and the heirs of his body. B dies in 1750 survived by child C, who dies in 1795 survived by Grandchild GC, who dies in1845 survived by Greatgrandchild GGC, who dies in 1906 without any surviving descendants. Under these facts, B's line of descendants is finally extinguished (i.e. becomes extinct) in 1906 and B's Fee Tail estate would only then come to an end even though B actually died in 1750."
A Fee Tail is like an infinite chain of life estates passing in the original grantee's line of descent from generation to generation.
Notice that although B could convey Blackacre to a third person, for example, to C, C received "only an estate for B's life because the restrictions imposed by De Donis prevented B from making any conveyance that would cut off the rights of B's issue or the reversioner. Thus, even though B conveyed to C, C acquired only an estate measured by B's life. Upon B's death, C's estate was extinguished and the property passed to B's heir of the body, if any, for life. If B had no living descendants at his death, or if B did but at some future point in time B's line of descendants became extinct, the property reverted to the grantor or his heir who had the reversion." (Moynihan)
Now for some examples (notice how you can "taille" or carve up the eligible heirs of the body in many ways):
1. Grutz conveys "to Arnold and the heirs of his body."
Arnold has a Fee Tail
Grutz has a Reversion
2. Grutz conveys "to Arnold and the male heirs of his body."
Arnold has a Fee Tail Male (only male descendants may inherit)
Grutz has a Reversion
3. Grutz conveys "to Arnold and the female heirs of his body."
Arnold has a Fee Tail Female (only female descendants may inherit)
Grutz has a Reversion
4. Grutz conveys "to Arnold and the heirs of his body by his wife Maria"
Arnold has a Fee Tail Special (only descendants of Arnold & Maria may inherit)
Grutz has a Reversion
5. Grutz conveys "to Arnold and the female heirs of his body by his wife Maria"
Arnold has a Fee Tail Female Special (hold the lettuce and mayo) (only female descendants of Arnold & Maria may inherit)
Grutz has a Reversion
