RODENTIA. 321 



forwards in the longitudinal direction, in correspondence with the 

 position of the transverse folds of enamel. Many of them build 

 nests, dig out complicated burrows, and lay up stores for the winter. 

 The latter usually possess cheek-pouches. Some fall into a deep 

 winter sleep at the cold time of the year, others migrate in large 

 flocks. They produce numerous young, some of them four or six 

 litters in the year, and possess, accordingly, a great number of 

 abdominal and thoracic mammae. Uterus usually completely divided ; 

 placenta discoidal. 



Fam. Leporidse. With, long ears, powerful hind legs, and short tail. Den- 

 tition : i 2. 5 (6 ) [i c. P-m- 3 ' 3 m> T In the prsemaxillse there 

 1 5 L I'l 0-0 3-3 J 



are two posterior accessory incisors {Duplicidentata). Lepus timidus L., 

 Hare; L. variabilis Pall. Alpine hare; L. cuniculus K., Rabbit ; Lagomys, Pikas. 

 L. alpimis F. Guv., barely a foot in length, Siberia ; L. princeps Richards, 

 Rocky Mountains. 



Fam. Subungulata. Grinders, -. The feet have naked soles, and end in 



front with four, and behind usually with three toes. Cavia aperea L., Aperea, 

 in Brazil and Paraguay ; C. colaya Schreb., the tame Guinea-pig ; Ccelogenys paca 

 L., the Paca, Brazil ; Dasyprocta aguti L., the Agouti ; Hydrochcerus capybara 

 Erxl., the Capybara, four feet in length, the largest of living rodents. 



Fam. Aculeata. With short, obtuse snout, and spines on the dorsal side of 

 the body. Cercolabes prehensilis L., the Kuandu, Brazil ; Erethizon dorsatux 

 L., North America ; Hystrix cristatus L., Porcupine, Italy and Spain. 



Fam. Octodoiitidae. Octodon Cumingii Beiin., Chili; Myopotamus coypm 

 Geoff., the Coypu, distributed from Brazil to Patagonia. 



Fam. Lagostomidae, Chinchillas. Eriomys lanigera Benn., the Chinchilla 

 Chili; Lagidium Ouvieri Wagn.; Lagostomus trichodactylus Brookes, Viskatscha . 



Fam. Dipodae. Jerboas. With very long hind legs, which serve for jumping, 

 and large, usually tufted, jumping tail. Jaculus labradorliis Wagn., Hiipfmaus : 

 Dlpus JEgyptius Hempr. Ehrnb., Arabia ; D. sagitta Schreb., Sea of Aral ; 

 Pedetes caffer 111., Cape jumping hare (Springhase), South Africa. 



Q 



Fam. Muridae. Mice. Grinders : -. With large eyes and ears, and long 



3 



sometimes hairy, sometimes ringed, scaly tail. Cricetus frumentarius Pall., 

 the Hamster ; with internal cheek pouches ; constructs subterranean passages 

 and chambers, in which it accumulates winter provisions. It passes through a 

 short winter sleep, and is very hurtful to corn-fields. Mus rattiis, L., House-rat, 

 Black Rat ; M. decumanus Pall., Grey Rat ; M. musculus L., House Mouse ; 

 M. minutus Pall, (pendvlinufi} ; Ilydromys chrysogaster Geoffr., Australia. 



Fam. Arvicolidae. Voles. With thick, broad head, rootless grinders, snort, 

 hairy ears and tail. Arvlcola amphibius L., Water-rat ; A. arvalis Pall., Field- 

 mouse ; A, agrestis L. ; Hypudceus glarcolus Schr. ; Myodes lemimis L., the 

 Lemming, on high mountains of Norway and Sweden, known by its migrations 

 in immense flocks before the approach of the cold weather. Fiber zibetkicus 

 L., North America. 



VOL. II. 21 



