COUES ON GEOMYS AND THOMOMYS G. BUBSARIUS. 227 
pilous character seen in that animal, but long and fluffy. The coat appears 
to be shed from before backward by a steadily progressing process, as wit 
nessed by the definite lines of demarcation frequently observed. 
The plumbeous basal portions of the hairs, uniform to the very roots all 
over the body, are of such extent, and the colored terminal parts so short to 
correspond, that more or less of tmVcolor appears on all but the most daintily 
prepared specimens, and plumbeous is the prevailing tone of the under parts. 
The normal coloration is a dull reddish-brown, or impure chestnut, of varying 
intensity, frequently with a still duller muddy-brown superficial cast difficult 
to describe. This is the character of the upper parts, where a dusky dorsal 
area may or may not be appreciable. It gives way. on the sides to the plum 
beous of the under parts, which is overlaid with a hoary-brown or muddy- 
gray. The lips, chin, feet, and even legs, and the tail, are usually more or 
less white, the extent and purity of this white being wholly indeterminate ; 
it is sometimes wanting; sometimes the tail is variegated with white and 
brown. There are also liable to be irregular white patches on the belly. 
The soles and palms, when not soiled by adventitious substances, are nearly 
colorless. The incisors, as usual, are orange-faced in the adult state. The 
claws are of an indefinite pale-brown color, often variegated with extravasated 
blood. 
The plumbago state, in which some specimens as large as any others are 
found, is entirely different, and does not appear to shade into the normal 
phase. Here the color is exactly that of a lead-pencil mark on white paper ; 
but such is the gloss of the fur that violet, purplish, or even brassy reflections 
are shown with different lights. It is an intensification of the ordinary plum 
beous basal portion of the hairs, and its extent over the whole fur. In this 
condition, white paws and tail, and other irregular patches of albinism, also 
occur. The plumbeous is seen in its purity only above ; below, the fur is 
pointed with muddy-brown or gray. 
HISTORY. Although its written history does not date so far back as the 
early notices of the u Tucan" (G. mexicanus], this species was the first to be 
introduced to notice under a scientific name, and with a (supposed) scientific 
description. Dr. George Shaw was the physician who attended at the birth 
of the species, which he called Mus bursar ius, giving a recognizable descrip- 
