466 MONOGRAPHS <>K NOETH AMERICAN EODENTIA. 



name of a Linnsean species of a family distinct from Zapodidce, and was also 

 used, by various of the older writers, both specifically and generically. Thus, 

 lacvlvs is a generic term used for the Jerboas by Erxleben (Syst. Nat. 404, 

 No. 38) in 1777, long before Zapus hudsonius had been discovered. It 

 should, therefore, not have been imposed upon any subsequently determined 

 generic type. But even according to the rule, custom or precedent, which 

 permits an author who subdivides an old genus to restrict the name of such 

 genus to any one of his new genera he may see lit, Jaculus is still inapplica- 

 ble to the present genus; for such restriction seems to have been first made 

 by Jarocki,* a Polish naturalist, who, in 1821, employed the term Jaculus for 

 certain pentadactyle species of Dipodidee, the name becoming, at his hands, 

 exactly equivalent to the subsequent Alactaga of Fr. Cuvier (Proe. Zodl. 

 Soc. 1836, 141), afterward altered, on account of its barbarous character, 

 to Scirtetes, by Wagner (Arch, fur Naturg. 1841, Bd. i, 119). Clearly, then, 

 if Jaculus is available for any modern genus, it must be for one of the Dipo- 

 didee, and can have nothing to do with the present case. It is as much out of 

 the question, in fact, as either Dipus or Gerbillus. 



So far as I am a»ware, Jaculus was first used in connection with the pres- 

 ent gemis by Wagler, in 1830 (Natiirl. Syst. Amphib. u. s. w.). In this 

 procedure, however, he was followed by no writers of note until A. Wagner.f 

 in his "Gruppirung derGattungen der Nager in natiirlichen Familien" u. s. vv. 

 (Arch, fur Naturg. 1841, Bd. i, p. 119), used " Jaculus Wagl." as equivalent 

 to, and instead of, Meriones Cuv. The name, however, did not come into 

 general employ in this connection until 1857, when Professor Baird adopted 

 it in the same sense which Wagler and Wagner had attached to it ; and his 

 example has been generally followed by the American school. 



2. The term Meriones was invented by Illiger in 1811 (Prod. Syst. 

 Mamm. et Avium, etc. p. 82, No. 32), to cover the Old World species "Dipus 



" Jarocki's work I have not been able to consult. The title ami reference, as given by A. Milne- 

 Edwards, alter Brandt, are:—" Zoologia Cayli Zwiertopisnio ogolne. Warszwie, 1821. pi. i,p.26." Milne- 

 Edwards observes : " Jaiocki reserva le nom goueriqnr de IHpus aux Gerboises dont les pattes posterieures 

 sunt tridactyles, et constitua sous le nom de Jaculus un nonveau genre pour les especes a pattes posteri- 

 eures pentadactyles". — ("Etudes pour servir l'histoire de la Faune Mammalogiqiie de la Cbiue," apud 

 H. Milne- Edwards's " Becherches," etc., tome i, pp. 140, 147. 4to, Paris, 1868-74). 



t Says Professor Wagner (torn. cit. 120) : " Hinsiehtlicb der Benennuug der amerikanischen Spriug- 

 inaiise crinuere ich, dass ibnen der Name Meriones, den Fr. Cuvier auf sie ubertriigt, uieht beigelegt 

 werden sollte, indem ilm Diiger an Nager der alten Welt vergeben hat ; ich bediene mich daber des von 

 Wagler vorgeschlageueu Namens Jaculus." That is to say, Professor Wagner objects to M. Cuvier's 

 transferring Illiger's Meriones to the American type, without seeming to be aware that he is doing 

 the same thing himsolf,— transferring Jaculus to this type. 



