tomys microdon microdon_~
Merriam.--GUATEMALA.--Huehuetenango: 2 mi. S San Juan Ixcoy, 9340 ft.,
10 (KU 65404-13--December 24 and 25, 1954); 3-1/2 mi. SW San Juan
Ixcoy, 10,120 ft., 4 (KU 65210, 65414-15, 65417--December 27 and 28,
1954). San Marcos: 3-1/4 mi. N, 3/4 mi. E San Marcos, 9500 ft, 1 (KU
65420--March 22, 1955). Totonicapan: 5 mi. ESE Totonicapan, 4 (KU
68897-900--July 17, 1955).

All the localities from which we have examined specimens fall within
the geographic range of the subspecies as mapped by Hooper (1952:168).
He examined six specimens of _R. m. microdon_ and listed external and
cranial measurements for only two specimens.

Average and extreme external measurements of 13 adults (7
males, 6 females) from the vicinity of San Juan Ixcoy are:
total length, 176.5 (168-187); length of tail, 105.8
(100-110); length of hind foot, 19.5 (19-20); length of ear
from notch, 16.8 (15-18). The average weight in grams of
these same specimens is 9.1 (8-11). Average and extreme
cranial measurements of 12 specimens from the same series (7
males, 5 females) are: total length of skull, 22.55
(21.6-23.0); zygomatic breadth, 10.82 (10.2-11.2); breadth
of braincase, 11.02 (10.6-11.4); depth of skull, 8.67
(8.4-8.9); interorbital constriction, 3.78 (3.6-3.9);
breadth of rostrum, 3.86 (3.6-4.0); length of rostrum, 8.33
(8.1-8.6); length of incisive foramen, 4.27 (4.0-4.5);
length of palate, 3.48 (3.2-3.8); length of upper molar
tooth-row, 3.25 (3.0-3.4).

~_Reithrodontomys mexicanus howelli_~ Goodwin.--GUATEMALA.--Baja
Verapaz: 5 mi. N, 1 mi. W [Santa Cruz] El Chol, 6000 ft., 3 (KU 65315,
65386-87--January 30, 1955). El Quiche: 1 mi. NE Nebaj, 6000 ft., 2 (KU
65275, 65277--December 19, 1954). Huehuetenango: 5 mi. E, 1 mi. N
Huehuetenango, 7000 ft., 2 (KU 65418-19--December 22, 1954). Santa
Rosa: 1 mi. WSW El Molino [= approximately 1 mi. S, 6 mi. E
Cuajiniquilapa], 1 (KU 71315--August 3, 1956).

The specimen from 1 mi. WSW El Molino is from within the range of the
subspecies _R. m. orinus_ as mapped by Hooper (1952:141), coming from a
locality to the southeast of the two westernmost localities shown by
him for _orinus_. This mouse is distinctly darker than any of the
specimens of _orinus_ discussed beyond, and is as dark as the darkest
_howelli_ seen by us. In addition to the specimens of _howelli_ listed
above, we have examined 12 from Prusia, Ch