The specimens upon which this paper is based were received from various parts of four Western States. Those of the first lot were from South Dakota and were sent to the writer by Prof. H. C. Severin of Brookings, S. Dak. Among these was one specimen labeled “Rivellia sp. n.?” by the late Dr. J. M. Aldrich. Later, other specimens were received from H. E. Jaques, Iowa; C. W. Sabrosky, Kansas; Maurice James, Colorado; and one specimen from North Dakota, received from C. E. Mickel.