126 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 97 
to Dr. W. H. Burt, of the University of Michigan Museum of Zoology, 
for the loan of material and permission to describe one of the speci- 
mens as a new species. Grateful acknowledgment is made to Karl 
P. Schmidt, chief curator of zoology of the Chicago Natural History 
Museum, and to Dr. Joao Moojen, curator of mammals of the Museu 
Nacional, Rio de Janeiro, Brazil, for the loan of specimens. 
All capitalized color terms are from Ridgway (‘Color Standards 
and Color Nomenclature,’’ Washington, 1912). 
ECHIMYS SEMIVILLOSUS SEMIVILLOSUS (I. Geoffroy) 
Nelomys semivillosus I. GEorrroy, Ann. Sci. Nat., ser. 2, vol. 10, p. 125, 1838 
(abstract of description); Mag. Zool., Paris, 1840, pp. 42, 50, pls. 23, 28, 
figs. 7-9. 
Type locality.—Cartagena, Department of Bolivar, Colombia. 
Distribution.—Lowlands of northern Colombia. As yet known 
only from the lower Rio Magdalena drainage system. 
Coloration.—Hairs of upper surface of body Ochraceous-Buff to 
Ochraceous-Orange medially, becoming paler laterally; sides grayish 
to Light Buff or Warm Buff; dorsum and sides with a mixture of 
wholly black or brown spines, spines punctulated with white to buffy, 
the punctulated spines most conspicuous on posterior half of back 
and base of tail; crown grizzled, nape and interscapular region blacker; 
white to buffy postauricular patches present; rostrum, sides of face 
below dark orbital rings whitish to buffy; outer sides of fore and hind 
legs like sides; fore and hind feet above gray with dark patches, toes 
gray. Underside of head, body, and limbs white lightly washed with 
buff. Base of tail like back, remainder light brown thinly covered 
with short hairs, the hairs brown proximally, becoming paler to gray 
terminally. 
Measurements (in millimeters, of three adults)—Head and body, 
207, 227, 220; tail, 218, 222, ; hind foot, 38, 39, 37; ear, 19, 18, 
17; condylobasal length, ——, 46.6, 48.9; zygomatic breadth, ? 
24.2, 25,6; length of nasals, 17.7, 16.2, 17.5; least interorbital width, 
14.2, 16.2, 17.5; braincase, width, , 19.7, 19.7; bullae, ahian 
by 12.6, 8.1 by 12.9; alveolar length of molar row, 12.0, 12.1, 11.6. 
Remarks.—The foregoing description is based on three adults 
taken in the Rfo Cesar and Rio Guaimaral region. Two immature 
individuals of the same series have the following external measure- 
ments: Head and body, 145, 153; tail, 154, 173; hind foot, 33, 34; 
ear, 16, 16. Although the tail is longer than the combined head and 
body length in the young, it may become proportionately shorter as 
erowth of the individual continues. In adults, tail length is subequal 
to, or shorter than, combined head and body length. Spines are 
completely lacking in the two young individuals; otherwise their 
pelage and coloration are as in adults. 
