[001] patruus magnus and triamita magna, and their heirs ad infinitum. And on the other [002] transverse [line], on the mother's side, if the avunculus and the matertera and all [003] heirs below them fail, then the brothers or sisters of the maternal grandfather or [004] grandmother are called,1 who are termed avunculus magnus and matertera magna, [005] and their heirs ad infinitum. Failing these, there then are called on the maternal [006] side the brother or sister of the greatgrandfather or greatgrandmother, the proavunculus [007] magnus or the promatertera magna, and their heirs ad infinitum. And thus [008] step by step are to be called the abavunculus magnus and abmatertera magna, the [009] atavunculus magnus and the atmatertera magna, and the triavunculus magnus and [010] the trimatertera magna, [by ascending the transverse line on the mother's side,] [011] and their heirs ad infinitum. And how the degrees of kinship are computed and the [012] number of degrees that separates one from another in the line of descent or ascent, [013] will appear more clearly to the eye in the figure given below.2
Of heirs who succeed not by succession but by substitution, by the modus of the gift.
[015] One may succeed or quasi-succeed another not by hereditary right, as heir, but [016] because of the failure of heirs or the commission of felony, as a chief lord-feoffor [017] succeeds to his escheat, a matter discussed above in the title on gifts.3 One may also [018] succeed or quasi-succeed another not by hereditary right or the right of succession, [019] as heir, but through the causa of substitution,4 by the modus of the gift, a matter [020] also discussed above in the same title,5 as where a donor in making his gift says, [021] Know etc. that I have given to such a one so much land with the appurtenances [022] to have and to hold to him and the heirs born of his body only. Here, since all [023] more remote heirs are excluded [and] the land is to revert to the donor by tacit or [024] express condition if the prescribed heirs fail, the donor may add these words to the [025] charter of gift: And if he has no such heirs, or if he has such and they fail, that the [026] land revert to another (a brother or stranger) to have and to hold to him and the [027] heirs born of his body, as was said above, and so to several successively. If the [028] first feoffee has no heirs of the prescribed class, no right descends to the substitute [029] by which he may bring an assise of mortdancestor on the seisin of the first feoffee, [030] in possessory right,6