One specimen from Batesland, South Dakota, is referred to _Z. h. pallidus_ but shows evidence of intergradation with _Zapus hudsonius campestris_ in the shape of the nasals, incisive foramina, and in breadth of the zygomatic arch. An animal from 3 mi. NE Ponca, Nebraska, is intermediate between _Z. h. pallidus_ and _Zapus hudsonius intermedius_ in size and shape of the auditory bullae and in the breadth of the pterygoid fossae, but since this individual shows more resemblance to _Z. h. pallidus_ in coloration and in the majority of cranial characters it is here referred to _Z. h. pallidus_. Specimens from Beemer, Nebraska, show an intergrading tendency toward _Zapus hudsonius intermedius_ in the reduced lateral bowing of the zygomatic arch and in shorter zygomata. Since these individuals resemble _Z. h. pallidus_ in the majority of characters they are referred to that race. An individual of _Z. h. pallidus_ from Pevely, Missouri, is to some extent an intergrade with _Z. h. intermedius_ of neighboring southern Illinois. Two individuals of _Z. h. pallidus_ from Mohawk Park, Oklahoma, are darker dorsally than, but otherwise similar to, specimens from the type locality. _Zapus hudsonius pallidus_ seems to be the terminus of a cline; this is a southward trend toward smaller size and lighter, brighter color. There is a similar clinal tendency in the jumping mice in eastern North America, and _Z. h. americanus_ from North Carolina, pronouncedly resembles _Z. h. pallidus_ from Kansas. _Specimens examined._--Total, 44, distributed as follows: KANSAS: _Brown Co._: Horton, 1. _Douglas Co._: Sec. 8, T. 123, R. 20E, 5-1/2 mi. N, 1-3/4 mi. E Lawrence, 10; _5 mi. N and 1-1/2 mi. E Lawrence_, 3; _Robinson Farm, 5 mi. N and 3 mi. E Lawrence_, 2; _4 mi. N, 2-1/2 mi. E Lawrence_, 1; Lakeview, 2; _7-1/2 mi. SW Lawrence_, 1. _Greenwood Co._: 1/2 mi. S Hamilton, 1. MISSOURI: _Cole Co._: Jefferson City, 2 (MO). _Jackson Co._: _no exact locality_, 1 (USBS). _Jefferson County_: Pevely, 1 (USBS). NEBRASKA: _Blaine Co._: _Dismal River, at Thomas-Blaine County line_, 1 (NGFP). _Boyd Co._: 2 mi. E and 15 mi. S Spencer, 1. _Buffalo Co._: Platte Meadows, Kearney, 1 (HM). _Butler Co._: 5 mi E Rising City, 1. _Cherry Co._: Niobrara River, 18 mi. NW Kennedy, 1; Ballard Marsh, 20 mi. S Valentine, 1 (JKJ); _Pony Lake Headquarters, Valentine Nat'l Wildlife Refuge_, 1 (JKJ). _Colfax Co._: _2 mi. S Schuyler_, 1 (JKJ). _Cuming County_: Beemer, 4 (USBS). _Dixon Co._: 3 mi. NE Ponca, 1. _Platte County_: _Columbus_, 1 (USBS). _Richardson Co._: 5 mi. SE Rulo, 1 (NGFP). OKLAHOMA: _Tulsa Co._: Mohawk Park, 2 (UM). SOUTH DAKOTA: _Bennett Co._: Batesland, 1 (FM). _Marginal records._--South Dakota: Batesland. Nebraska: 3 mi. NE Ponca; Beemer; 5 mi. SE Rulo. Missouri: Pevely. Oklahoma: Mohawk Park. Kansas: 1/2 mi. S Hamilton. Nebraska: Platte Meadows, Kearney; Ballard Marsh, 20 mi. S Valentine; Niobrara River, 18 mi. NW Kennedy. =Zapus hudsonius preblei= new subspecies