During the past five years I have collected and measured 14 6 and 3 9 adult specimens pertaining to this species. All were collected in McLennan Co., Texas, from the South Bosque River and Hog Creek. E.B. WILLIAMSON (1909, Proc. U.S. natn. Mus. 37: 369-398, pis. 35-36) published measurements of paciftca based on 25 d and 7 9 specimens, most of these from Indiana, save for I d and 19 from Waco, Texas, I 9 from Milwaukee, Wisconsin, 1 d and I 9 from Mahomet, Illinois, and 1 d from Kappa, Illinois. His measurements (abdomen inch app.: d 48.5- 53.0 mm, mean 50.9; 9 46.5-53.5 mm, mean 50.6; — hind wing: d41.5-48.0 mm, mean45.3; 9 44.5-49.5 mm, mean 47.3), given for the entire material, without distinction between localities, indicate that paciftca is approximately the size of M. annulata Hag. and M. georgina (Sel,), My specimens, however, are notably smaller than those species and Williamson’s specimens of M. paciftca. Mrs. L.K. Gloyd (Ann Arbor, Michigan) most kindly sent to me the measurements of the paciftca specimens in the E,B. Williamson Collection, University of Michigan, Ann Arbor, Michigan. All of these are from Bluffton and the Wabash River, Wells Co., Indiana, except for I 9 from Murray Co., Oklahoma. They are shown in Table 1 along with my McLennan material.