A =NUMBER AVERAGED AND s.e.x B = Greatest length of skull C = Zygomatic breadth D = Breadth of braincase E = Interorbital breadth F = Depth of cranium G = Length of rostrum H = Breadth of rostrum I = Length of incisive foramen J = Length of palate K = Alveolar length of maxillary tooth-row --------------------------+----+----+----+---+---+---+---+---+---+---- A

B

C

D

E

F

G

H

I

J

K --------------------------+----+----+----+---+---+---+---+---+---+---- _R. m. dychei_, Douglas County, Kansas

Av. 17 (11 male, 6 female)

20.9

10.5

10.1

3.1

7.9

7.2

3.8

4.3

3.5

3.3 Minimum

20.4

10.0

9.8

3.0

7.7

6.8

3.6

4.0

3.2

3.1 Maximum

21.9

10.9

10.3

3.3

8.2

7.9

4.0

4.5

3.9

3.4 --------------------------+----+----+----+---+---+---+---+---+---+---- Cherry County, Nebraska

Av. 20 (14 male, 6 female)

21.0

10.9

10.3

3.1

7.9

7.3

3.8

4.4

3.6

3.5 Minimum

20.4

10.0

9.8

2.9

7.5

6.8

3.5

4.3

3.4

3.2 Maximum

22.1

11.3

10.7

3.3

8.4

7.8

4.1

4.7

3.9

3.7 --------------------------+----+----+----+---+---+---+---+---+---+---- _R. m. aztecus_, San Juan County, New Mexico, and Montezuma County, Colorado

Av. 10 (6 male, 4 female)

21.5

10.8

10.2

3.1

8.1

7.7

3.7

4.5

3.4

3.5 Minimum

20.5

10.4

9.9

2.9

7.9

7.2

3.5

3.9

3.1

3.2 Maximum

22.7

11.1

10.6

3.3

8.4

8.2

3.9

4.8

3.7

3.7 --------------------------+----+----+----+---+---+---+---+---+---+----

LITERATURE CITED

ALLEN, J. A.

1893. List of mammals collected by Mr. Charles P. Rowley in the San Juan region of Colorado, New Mexico and Utah, with descriptions of new species. Bull. Amer. Mus. Nat. Hist, 5:69-84, April 28.

1895. On the species of the genus Reithrodontomys. Bull. Amer. Mus.

Nat. Hist, 7:107-143, May 21.

BENSON, S. B.

1935. The status of Reithrodontomys monta.n.u.s (Baird). Jour. Mamm., 16:139-142, 1 fig., May 15.

BLAIR, W. F.

1954. Mammals of the Mesquite Plains Biotic District in Texas and Oklahoma, and speciation in the central gra.s.slands. Texas Jour. Sci., 6:235-264, 1 fig., September.

DALQUEST, W. W.

1948. Mammals of Washington. Univ. Kansas Publ., Mus. Nat. Hist., 2:1-444, 140 figs., April 9.

HALL, E. R., and K. R. KELSON

1959. The mammals of North America. Ronald Press, New York, vols.

1:x.x.x + 1-546 + 79 and 2:viii + 547-1083 + 79, 553 figs., 500 maps, 178 unnumbered text figs., March 31.

HILL, J. E., and C. W. HIBBARD

1943. Ecological differences between two harvest mice (_Reithrodontomys_) in western Kansas. Jour. Mamm., 24:22-25, February 20.

HOFFMEISTER, D. F., and J. E. WARNOCK

1955. The harvest mouse (Reithrodontomys megalotis) in Illinois and its taxonomic status. Trans. Illinois Acad. Sci., 47:161-164, 1 fig.

HOOPER, E. T.

1952. A systematic review of the harvest mice (genus Reithrodontomys) of Latin America. Misc. Publ. Mus. Zool., Univ. Michigan, 77: 1-255, 9 pls., 24 figs., 12 maps, January 16.

HOWELL, A. H.

1914. Revision of the American harvest mice (genus Reithrodontomys).

N. Amer. Fauna, 36:1-97, 7 pls., 6 figs., June 5.

1935. The harvest mice of the San Luis Valley, Colorado. Jour.

Mamm., 16:143-144, May 15.

LAYNE, J. N.

1959. Growth and development of the eastern harvest mouse, Reithrodontomys humulis. Bull. Florida State Mus., 4:61-82, 5 figs., April 27.

VERTS, B. J.

1960. Ecological notes on _Reithrodontomys megalotis_ in Illinois. Nat. Hist. Misc., Chicago Acad. Sci., 174:1-7, 1 fig., July 25.