California Code, Probate Code - PROB § 247

(a) Where a will, trust, or other instrument calls for property to be distributed or taken “in the manner provided in Section 247 of the Probate Code,” the property to be distributed shall be divided into as many equal shares as there are living members of the nearest generation of issue then living and deceased members of that generation who leave issue then living.  Each living member of the nearest generation of issue then living is allocated one share, and the remaining shares, if any, are combined and then divided and allocated in the same manner among the remaining issue as if the issue already allocated a share and their descendants were then deceased.

(b) Unless the will, trust, or other instrument expressly provides otherwise, if an instrument executed on or after January 1, 1986, calls for property to be distributed or taken “per capita at each generation,” the property shall be distributed in the manner provided in subdivision (a).

(c) If a will, trust, or other instrument executed before January 1, 1986, calls for property to be distributed or taken “per capita at each generation,” the property shall be distributed in the manner provided in subdivision (a), absent a contrary intent of the transferor.