Arthur sends thanks for the two specimens of rusts on Potentilla and the data regarding them. Number 4833 is the type collection for 'Aregma triarticulatum' and the host is apparently Potentilla Canadensis. Most collections of this host show the leaves have long, straight hairs on the veins, but none on the rest of the leaf. The leaf fades to a yellowish brown colour. He would like to know if this agrees with the specimen in the RBG Kew Herbarium. Number 6125 is incorrectly referred to 'Aregma triarticulatum'. The host is Potentilla pennsylvanica and the rust is Phragmidium potentillae. Annotation states that the specimen host of 4833 is so small that it is impossible to determine whether it is P. canadensis or not. The marginal teeth are larger than those of the herbarium specimens but the hairs agree in character. [See also letter at folio 201/224.] Page 1 of 1.