In the article on Alnus crispa published in CASTANEA for June, 1960, the occurrence of this plant in Pennsylvania was overlooked. It has been collected at two localities, one in Tioga County, near the northern border (Owassee, lat 41°43′, long. 77°27½’, Wahl No. 15870, June 21, 1955) and the other in Bedford County (Martin Hill Fire Tower, lat. 39°50′, long. 78°32½’, Berkheimer No. 9883, July 15, 1948), this near the southern border only 50 miles northeast of West Virginia. The disjunction of this taxon is thus not nearly so extreme as implied in the article. Plant geographers working on plants the distribution of which may cross Pennsylvania would do well to consult the Porter herbarium at the Academy of Natural Sciences of Philadelphia, and the extensive! more recent collections at the University of Pennsylvania, in which latter the above cited specimens are filed.