ZAPODIDiE—ZAPUS— SYNONYMY AND CHARACTERS. 



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Trunk enlarged posteriorly, in correlation with tlie shortness of the fore limbs 

 and great elongation of the hind ones, especially of thfc pes (cf. Murida 

 except Gerbillince) ; nevertheless, the pes with five perfect and separate meta- 

 tarsals, and five functionally developed digits (cf Dipodlda, Pedetida). Claws 

 not peculiar (cf. Pedetidai). Tail greatly exceeding the trunk in length (cf 

 most Murida), very slender, scant-haire<l (cf Dipodida, Pedetida). Pro- 

 gression saltatorial. 



Other characters of less value an; adduced as generic under the head 



of Zapus. 



Genus ZAPUS, Coues. 



< Dipm, Bp., ZiMMEi'.MANN.Oengr. Gescb. ii, 1780, 358.— Davieh, Trnim. Linn. Soo. iv, 1798, IST).— Barton, 



Tranii. Aiuer. Fliilos. Sac. ir, 1799, 114. 



< Mui, sp., ZiMMKKMANN, Plmiii. Arkt. Zool. i, 1787, 131 (Mm longipa, Zimni., nee anct.). 



< Gerbillvs, Bp., Desmakest, Mamm. ii, 182*^, 331 ^not type). 



= Mirionei, Fu. CuviRR, Denta des Mumm. 18*25, 187 (type. But nut itcrionea of Illlger, Prod. 1811, 83, 

 which is based on DxpHS (anuiricinus and D. menrfianua). 



< Meriones, Audubon &. Bachman, Quad. N. Am. ii, 18&1, 251 (used in au extended sense, to include 



Old World species of DipodidcB). 

 ■=J<KulHt, Waolbr, NatUrl. Syst. Anipbib. 18:10, 23 (type. Bnt not of Jarocki, 1821, nor of early authors).— 



Wagner, Arch, flir Naturg. 1841, Bd. i, 119.— Baird, Mamm. N. Am. 1857, 429.- Ai^ston, 



Proc. ZdGI. Soc. Lond. 1876, 89. 

 = i!apiia, CouKS, Bull. U. 8. Oeol. Sucv. Terr. 2d ser. No. 5, 1875, 253 (type). 



Chars. — With well-developed internal cheek-pouches. Digits of the 

 hand five, the first of which is rudimentary, with a flat, blunt nail ; palms 

 naked, granular, and tuberculate Digits of the foot five, all functional, and 

 with perfect claws and basal ' ebs ; sole naked throughout, the heel smooth, 

 the rest granular and tube-\,ulate. Meatus of the ear capacious, closed with 

 large antitragal and tragal flaps. Pelage coarse and hispid. Size small; 

 configuration modified from an ordinary Murine shape ; physiognomy peculiar. 



Other characters are fully detailed in the description of the species 

 beyond. Here I may refer again, more in detail, to the grounds (^nriefly set 

 forth when I proposed the name Zapus) upon which a new designation was 

 given to the well-known genus; tor I insist that a new name was required. 



Tiie generic type in question has been successively called Dipm, Mus, 

 Oerbillus, Meriones or Meriones, Jaculwt, and Zapus. Which of these names 

 is tenable ? 



The first three — Dipus, Mus, and Oerbillus — are too obviously inappli- 

 cable to be brought into the question at all. Their unavailability in this con- 

 nection is now conceded by all. 



1. Jaculus, or, in its older forms, Jaculus and lacvlos, was the specific 

 30 M 



