1884.] 



MURID.C KKOM CENTHAL PERU. 



451 



and H. bimaculatus ; tlie general tendency being to a disappearance of 

 the tropical and northern Mouse- and Dormouse-like subgenera 

 Rhipidomys, Vesperimus, and Oryzomys, with the appearance and 

 increase of the Vole- and Hamster-like Habrothriv and Calomys — a 

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

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

 as we go northwards from tropical to temperate and arctic regions. 



As in the former paper, the measurements of a series of specimens 

 is given in most cases ; but 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, Tsch. 

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



Head 

 and body. Tail. 



a. 2 150 198 



b. 2 I 27 '78 



[H. latimanus, Tomes, $ . 123 165 



Hind Forearm Ear- Muzzle 

 foot 1 , and hand, conch, to ear. 



345 425 16-5 34-0 

 33-0 38-4 1 5 5 310 

 28-0 35-5 127 30"0] 



Skull-dimensions. 



b 



[//. latimanus. 



[i/. latimanvs. 



Total 

 length. 



. 358 

 . 345 



Palatal 

 length 3 . 



18-0 

 16-6 



Basal 



length 3 . 



33-2 

 320 



Palatal 

 foramen. 



7-5 



6-8 



Zygom. 

 breadth. 



195 

 18-4 



Molar 



series. 



C-9 

 5-5 



Back of inci- 

 sors torn'. 



9-2 



8-9] 



Interorbital 

 constriction. 



60 

 5*6 



Basal 



axis 4 . 



11-1 



110 



Lower 

 jaw 8 . 



20-9 



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

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



1 Without claws. 



2 From the front of the prtemaxilla; to the most posterior point of either of 

 the occipital condyles. 



3 From the front of the prsemaxilla? to the end of the bony palate. 



4 From the central point of the posterior edge of the basioccipital lo the 

 anterior edge of the lower surface of the basisphenoid (not prmsphenoid , as 

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

 combined lengths of the basioccipital and basisphenoid, that of the pr»- 

 ephenoid being unattainable unless the skull is bisected. 



* Bone only- 



