A.C. Zieber 1959 Reithrodonmys rawienvris San Pablo Creek (salt marsh), Richmond, Contra Costa Co., Cal. JULY 7-8 Several taken by Geo. F. Fisher on or near study area. Only the largest showed the smallest bit of fat. Took also Microtus mys. 5 bank mouth San Rafael Creek, etc .... JULY 8 See Journal this date. (No Reithrodonys taken this marsh locality!) San Pablo Creek (salt marsh), Richmond, Contra Costa Co., Cal. JULY 18-19 11 or 12 taken there 2 days in same years by Geo. F. Fisher. 2 saved as comp eted only. Only largest 1 of 2 showed any fat. Mammary tissue heavy on 2 f's. Reithro. megarhis also taken (5). The rawienvrus seem generally larger y, of course, larger (+ 200-800g) than the megarthrs. The former also have long, dark guard hairs even in young mice, that the megarhys seem to almost lack.