REVISION OF THE JUMPING MICE OF THE GENUS ZAPUS. 9 



find out much about it. Hiberuation varies with the locality, but usu- 

 ally begins about the time of the first heavy frosts and lasts uutil 

 spring. The fall pelage is usually assumed and the animals become 

 exceedingly fat before entering winter quarters. Although they often 

 lay up stores of food in nests or burrows during summer, it is not known 

 that they use this food during winter. The animals are generally found 

 singly (sometimes in pairs) in nests in holes at a depth varying from 

 a few inches to 2 or 3 feet below the surface. They lie rolled up like 

 a ball with the feet close together and tail curled about them. If 

 removed from the nest and subjected to a moderate degree of heat they 

 revive and in the course of a few hours move about freely, but gen- 

 erally resume their lethargic state if again exposed to cold. The pulse 

 and respiration are very slow. 



Hibernation sometimes takes place in a nest above ground. Dr. 

 A. K. Fisher tells me that some years ago a Zapus was brought to him 

 at Lake George, iSTew York, which some men at work in the woods had 

 found hibernating in an elaborate nest of grass and moss, exposed by 

 moving a log. This nest was destroyed, but when the animal was 

 given material it constructed another, in which it resumed its inter- 

 rupted sleep. It was occasionally awakened, and observations were 

 taken on its weight, respiration, and heart beats, after which it would 

 relapse into its state of lethargy. 



NOMENCLATURE. 



Five generic and 30 specific and subspecific names have been applied 

 to various forms of Jumping Mice now included in the genus Zapm. 

 In order to discuss the different species and subspecies intelligently it 

 becomes necessary to separately consider each of these names, which 

 may be taken up alphabetically. 



GENERIC NAMES. 



Dipus Zimuiermann, Geog. Geschichte des Menschen u. vierfiissigeu 

 Thiere, II, p. 358. 1780. The original description of the genus Dipus 

 included six species: T>. jaculus, D.sagitta, Yerbua capensis ( = Mus 

 cafcr), D. longipes, D. tamarichms and D. hudsonius. The name was 

 subsequently restricted to the Old World jerboas. 



Gerbillus Desmarest, Nouv. Diet, d'Hist. Nat., XXIV, p. 222, 1804. A 

 genus of Old World rodents allied to Meriones. Four nominal species 

 of American Jumping Mice were referred to this genus by Katines<|ne 

 in ' Prrcis des Decouv. somiologiques ' (p. 14, 1814), and Am. Monthly 

 Magazine (III, p. 440, Oct., 1818). 



Meriones Illiger, Prod. Syst. Ma mm. et Avium, p. 82, 1811. The name 

 Avas originally proposed by Illiger for a group including Dipun tumnn- 

 cinus and />. incridiinitis. Cuvier apparently proposed it independently, 

 twelve years later, for the American Jumping Mouse (Dents des Mamm., 

 pp. 187, 250, 1823). 



