1884.] 



MURID^- FROM CENTHAL PERU. 



451 



and H. bimaculatvs ; the genernl tendency being to a disappearance of 

 tlie tropical and northern Mouse- and Dormouse-like subgenera 

 Rhipidomys, Vesperimus, and Oryzomys, with the appearance and 

 increase of the Vole- and Ilamster-like Habrothrix and Calomys — a 

 change that is curiously paralleled in the Old World by the gradual 

 supersession of Mus and Myoxus in favour of Arvicola and Cricetus, 

 as we go northwards from tropical to temperate and arctic resion^. 



As in the former paper, the measurements of a series of s[K'cimen3 

 is given in most cases ; hut this time in millimetres, which are used 

 in deference to universal custom, although, in the case of small 

 mammals, they are scarcely so convenient for practical working as 

 the inches and tenths hitherto employed. 



The species not obtained by M. Stolzmann are distinguished by an 

 asterisk, while their number in the paper on his collection is placed 

 after the names of those that were contained in it. 



1. HoLOCHiLus (Nectomys) apicalis, Peters. S. No. 3. 



a tog. Seven immature specimens. Amable Maria and Maraynoic. 



2. *Hesperomys (Rhipidomys) leucodactylus, Tseh. 

 a, b. Two specimens, b from Amable Maria, 2000 feet. 



Head 

 and body. Tail. 



a. 2 I.i0 198 



l>. 2 127 178 



[H. latimanus, Tomes, ? . 123 165 



Hind Forearm Ear- Muzzle 

 foot^ and hand, conch, to ear. 



34-5 42-5 16-5 34-0 

 33-0 38-4 15-5 310 

 28-0 35-5 127 30-0] 



Skull-dimensions. 



Fur rather crisp, and of medium length. General colour above 

 brownish grey, below white, the bases of all the hairs slate. Dark 



' Without claws. 



^ From the front of the przemaxillse to the most posterior point of either of 

 the occipital condyles. 



3 From the front of the prsemaxilke to the end of the bony palate. 



^ From the central point of the posterior edge of the basioccipital (o the 

 anterior edge of the lower surface of the basisphonoid (not prasphenoid , as 

 accidentally staled P. Z. S. 1882, p. 65, footnote). This measurement gives the 

 coiobined lengths of the basioccipital and basisphenoid, that of the pras- 

 •phenoid being unattainable unless the skull is bisected. 



• Bone only. 



