1898.] NATURAL SCIENCES OF PHILADELPHIA. 121 



foot is 24 mm. from end of heel to end of claws; the tail 45 mm. 

 long, these dimensions being taken from the dry specimen. No 

 measurements for any of the specimens in the collection were recorded 

 by the collectors. 



2. Mus humiliatus M. Edwards. Pekin River Rat. 



An adult female, No. 4,598, from the steep banks of a stream at 

 Shiao Ho Tzu undoubtedly represents Milne Edwards' species de- 

 scribed 3 from the environs of Pekin, and with whose measurements 

 and plate it closely agrees. Edwards states that it represents Mus 

 rattus in China, an unaccountable statement, perhaps a slip of the 

 pen for Mus decumanus, as its external and cranial characters are 

 very close to the short-eared, brown-backed, gray-bellied short-whisk- 

 ered Norway Rat. Its short tail and small cranium, however, easily 

 distinguish it from decumanus. The skull of the specimen is 37.5 mm. 

 in occipito-nasal length and 18.5 mm. in its greatest zygomatic ex- 

 panse. The nasals are relatively short, not reaching so near to the 

 superior termini of the premaxillaries as in decumanus or rattus. 

 The relations of this species to Mus caraco Pallas are seemingly close 

 and it may yet prove that humiliatus is only a subspecies of caraco. 



3. Mus sp. ? 



The scalp and skull of an adult, long-whiskered, long-eared and 

 long-nosed rat, No. 4,599, taken southeast of Dolonnor apparently 

 represent a species of slender and elegant proportions, with a skull 

 nearly as long as in the specimen of humiliatus above recorded, but 

 with a greatly diminished zygomatic width and cranial depth. 

 These characters and the great relative length of rostrum put it in 

 the Mus rattus group. Its cranium is much smaller and more slender 

 than M. rattus alexandrinus and the mandihles are unusually nar- 

 row and weak for a Mus. The upper head is yellowish-brown, 

 heavily lined with black, darkest around eyes. Ears brown-gray ; 

 lips white; throat yellowish-white ; gray of cheeks broadly bordered 

 iuferiorly by ochraceous buff which probably extended increasingly 

 along neck and sides of body. 



4. Alactaga annulata (M. Edwards). Subsp. ? Jerboa, Khin Gan. 



A young female Jerboa, No. 4,597, about two-thirds grown, from 

 all appearances should be classed under the above name. As would 

 be expected, its immaturity is evinced by the darker pelage over the 



3 Recher. Mam., 1868-74, p. 137. 

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