1 1 
Colour : On upper surface, grizzled brownish gray, deepening to 
nearly black in lines and blotches on the middle of the back, 
shoulders, nape, and about the head, where a line runs obscurely 
above the eyes to meet its fellow on the snout in front of the 
radiating point. Base of the dorsal fur pale gray with some tips 
whitish, others black and brown, the mixture, aided by the long 
hairs, which are pale at the base, dark in the middle, and nearly 
white at the tip, producing the grizzled appearance Cheeks, limbs, 
sides of rump, and scrotal region rufous brown ; fore and hind feet 
blackish brown. Below, from upper throat to penis, and on inner 
surface of limbs, isabelline. Incisors : Upper, pale brown ; lower, 
isabelline. Tail, above and below, dark brown on basal moiety, 
paler on apical. Whiskers, black. 
Skull : Premaxillaries deep (14mm.) ; posterior edge of infra- 
orbital fissure straight, without projection anterosuperiorily ; supra- 
orbital edge at junction of zygoma and frontal with a strong process 
posteriorly, at junction of sqamosal and frontal elevated into a pro- 
nounced ridge ; parietal ridges moderate, frontals conspicuously 
tumid anteriority ; incisive foramina as long as the molar series, not 
nearly reaching the teeth, wide (disclosing a broad vomer) with a 
contraction near the anterior end ; auditory bullae thickly walled, 
its orifice directed unusually backward. 
Teeth: Upper molars in a series, 16mm. long ; first molars 5mm. 
broad, and in breadth six-fifths of that of the intermediate palatal 
space ; third, as long as the second but narrower, width 3mm. ; first 
molars with a central row of three horseshoe folds, two ear-shaped 
folds, on the inner, and two much smaller on the outer ; the second 
has two central and two inner folds, like the first, but only one on its 
outer side ; the third is like the second, but has no fold on its outer 
side ; these folds form regular longitudinal rows, slightly divergent 
posteriorily. Lower molars in a series, equally broad fore and aft, 
the enamel folds on each form double loops, three on the first tooth 
(the foremost very small) and two on each of the second and third ; 
the bases of these loops are directed forward, those of the upper teeth 
backward. Altogether, the teeth, in breadth and armature, have no 
little resemblance to those of Mastacomys. Incisors not grooved. 
Habitat : The collector states that this rat is arboreal. 
The structure of the teeth — approaching that of Mastacomys ; 
features of the skull — reminding us of Uromys in an exaggerated 
form, the peculiar lepidosis of the tail ; the huge size and masstve- 
ness of the body ; the radiation of the hair of the head — reminding 
us of the tree kangaroos, | and thus significant of strictly arboreal life : 
these form an assemblage of characters which seems to confer generic 
rank. 
But, though this rat came to me with an assurance that other 
specimens obtained were so disposed of that it could not have been 
named, I feel hardly justified in running the risk of perpetrating a 
synonym, otherwise I should propose for it the name Dendrosminthus 
aroaensis. 
