NO. 12G9. A XDA MA X A XD XICOBA R MA MMALS— MILLER. 761 
antorbital foramen is as broad as in Miis validus^ but the foramen is 
widely open below, as in Mus vociferans. These characters are very 
apparent in this view of the skull. Viewed from the side the skull 
closely resembles that of 2[us vociferans^ except for the peculiarities 
already mentioned. Zygomatfi much more slender than in the allied 
species. Viewed from beneath the skull shows its most striking" char- 
acters. The floor of the braincase is essentially like that of Mus 
vocifercms, though the audital bulla? are distinctly larger than in the 
mainland animal. In form the bulhe do not differ very materially 
from those of 2£us voclferdns^ though they are somewhat more inflated 
anteriorh^ Palate and rostrum very unlike those of any of the allied 
species, the differences due to the combined reduction in size of the 
teeth and elongation of rostrum. The length of toothrow is contained 
fully twice in length of diastema, instead of about once and a half, as 
in Mus vociferans and Mus validus. The incisive foramina share in 
the elongation of the rostrum to such an extent that they are much 
longer than the toothrow instead of distinctly shorter. Except that 
it shares in the general slender form of the skull the mandible shows 
no characters of importance. 
Teeth. — The teeth differ from those of 3fus vociferans in size only, 
as the enamel pattern of the two species is similar throughout. 
2L'asurcnients. — External measurements of type: Total length, 442 
mm.; head and body, 249; tail, 193; hind foot, 47 (45); ear from 
meatus, 24; ear from crown, 20; width of ear, 16. Average of ten 
adults from the type locality: Total length, 437 (415-465); head and 
body, 241 (220-260); tail, 198 (192-212); hind foot, 48 (47-50); hind 
foot without claws, 46 (45-48). For detailed measurements see table, 
page 764. 
Cranial measurements of largest specimen: Greatest length, 55.4 mm. 
(56);' basal length, 50 (47.6); basilar length, 47 (44.6); palatal length, 
28 (25); least width of palate betw^een anterior molars, 6 (5); diastema, 
18 (14.8); length of incisive foramen, 10.6 (8); combined breadth of 
incisive foramina, 3.8 (3.8); length of nasals, 22 (21.4); combined 
breadth of nasals, 5.4 (6.2); zygomatic breadth, 25 (25.8); interorbital 
breadth, 9 (9); breadth of braincase above roots of zygomata, 18 (20.4); 
mastoid breadth, 19 (18.8); occipital depth at front of l)asioccipital, 
14.6 (14); frontopalatal depth at posterior extremit\" of nasals, 13 (13.6); 
least depth of rostrum immediatelv behind incisors, 9.8 (11); mandible, 
31 (30.6); maxillary toothrow (alveoli), 8.2 (11. S); width of front upper 
molar, 2.4 (3); mandibular toothrow (alveoli), 8.4 (10). 
Specimens examined. — Eighteen, all from the t3'pe locality. 
Reinarhs. — In general appearance Mus stoicus resemliles Mus 
validus, but the skull is much more slender. It is, however, in no 
way distantly related to the large rats of the Malay Peninsula. 
' Measurements in parenthesis are those of the type ol Mus vociferam. 
