Carrizo is indistinguishable from Troyer and of the same parentage. Savage and Gardner (1965) have recently presented convincing evidence that Carrizo and Troyer are in fact a single clone which originated as the zygotic seedling (CPB 4-5019) from a cross of Washington navel and trifoliate orange made by the senior author in 1909 under the direction of W. T. Swingle of the U.S. Department of Agriculture instead of two sister seedlings as had been assumed (Mortensen, 1954). In 1923, Swingle had 200 seedlings of this then unnamed clone sent to the Winter Haven substation (No. 19) near Carrizo Springs, Texas. In 1938, he suggested it be named Carrizo, either forgetting that he had already given it the name Troyer in 1934, which seems unlikely, or because he failed to recognize its identity, which seems surprising. Bitters reports that its field performance has differed somewhat from Troyer, which is difficult to understand in light of the conclusions set forth above.