MAMMALS OF NORTHERN COLOMBIA—HERSHKOVITZ 139 
Description of holotype-—Back and head Ochraceous-Orange mixed 
with black, a broad band of stiff black-tipped spines on middle of 
back extending as a line of softer spines over rump to base of tail; 
crown and rostrum heavily lined with black; sides like back but with a 
lighter mixture of black and becoming paler toward the sharply 
defined white underparts. Inner side of thigh Cinnamon-Brown, 
hind foot brown; foreleg and forefoot paler. Tail above dark brown, 
beneath sharply defined flesh color. 
Measurements (in millimeters).—Those of the holotype followed by 
the means and extremes of the adults, including the holotype, of the 
type series. Head and body, 220, 228 (224-234, seven specimens); 
tail, 162, 158(152-171, five specimens); hind foot, without claw, 48, 
48(46-51, seven specimens); ear, 22, 24(22—26, seven specimens); 
greatest length of skull, in two paratypes, 54.4, 60.0; zygomatic 
breadth, 26.5, in three paratypes, 27.2, 27.6, 28.5; length of nasals, in 
four paratypes, 20.4, 23.0, 23.3, 25.0; alveolar length of molar row, 
9.3, 9.2(8.7-9.6, seven specimens). 
Remarks.—Specimens of P. guyannensis gularis and P. hendeei 
were taken in the same localities as those of P. quadruplicatus. The in- 
dividuals representing the three species are quite readily distinguished 
from one another. However, most of the characters that separate 
P. quadruplicatus from them lose their value when comparisons are 
extended to members of the same species from outlying regions. The 
composite nature of P. guyannensis contributes considerably to this 
difficulty. Nevertheless, quadruplicatus is always distinguishable 
from both guyannensis and hendeei by the pattern of its. molariform 
teeth. 
The dental characters upon which specific distinction is based are 
not limited to P. quadruplicatus. Isolated populations of the guadru- 
plicatus group occur in the Amazonian region and in Central America. 
As noted, the spiny rat recently described by Kellogg as P. “‘semispino- 
sus’’ ignotus, from Pearl Island, off the coast of Panama, is referable 
to this group. The Proechimys with the quadruplicate pattern of the 
molariform teeth occurring on the mainland of Central America cannot 
be properly identified without comparing specimens with the types of 
all previously described forms from that region. The teeth of the 
type of the Costa Rican rubellus are too worn for exact determination 
of their pattern. The writer’s notes on the types of centralis and 
chiriquensis lack this data, and it is to be presumed that these rats, 
like panamensis, do not show the complete quadruplicate pattern. 
Reliance cannot be placed upon “‘topotypes,”’ or even “‘paratypes,”’ 
for dental determinations, as two or more species of very similar 
appearing spiny rats may occur in the same locality. 
No doubt additional specimens of P. quadruplicatus are represented 
in museum collections. Osgood (1944, p. 200) has given a description 
