308 A new Jerboa from China. 



The discovery of this Jerboa extends very greatly the 

 known range of the three-toed Jerboas, which had hitherto 

 not been recorded east of Central Asia. 



This animal, with its close allies D. sag'itta and D. deasyi, 

 is clearly distinct generically from the other three-toed 

 Jerboas, and in finding a name to use for it I have had to 

 examine the generic nomenclature of the group with such 

 care and completeness as to enable me to claim the position 

 of "first reviser" in the selection of types for certain of the 

 generic names. 



The genera in question, with their characters and types, 

 would appear to be as follows : — 



Jaculus, Erxl., 1777. Type Jacidus jaculus (Musjacidus, Lirji.), the 



smaller Egyptian Jerboa. 

 Three hind toes. Three cheek-teeth only. 



Tvpe selected by tautonyrny, " Mus jaculus ' : being placed as a 

 synonym of Jacidus orientalis. 



Dipus, Zimm. * Geogr. Gesch. ii. p. 354 (1780). Type Dipus sagitta 

 (Mus sagitta, Pall.). 



Three hind toe3. Four upper cheek-teeth. 



The other species being exotic and otherwise unsuitable, the type of 

 this name has obviously to be either Mus jaculus, Pallas (nee Linn.), 

 the five-toed Russian Jerboa, or M. sagitta, Pall., the small three-toed 

 species. Both elimination and expediency indicate that the latter should 

 be selected as the type. 



Allactaga, F. Cuv. P.Z. S. 1836, p. 141. Type Mus jaculus, Pall. 

 Five-toed Jerboa. 



Scirtopoda, Brandt, Bull. Ac. Petersb. ii. p. 212 (1844). Type Dipus 

 mauritanicus, Duv . (equal or closely allied to Jaculus gerboa, Oliv., 

 the large Egyptian Jerboa). 



Hai/ticus, id. t. c. p. 213. Type Dipus halticas, 111. 



Haltomys, id. t. c. p. 215. Type Dipus mauritanicus, Duv. 



None of Brandt's names standing for valid groups there is no need to 

 explain in detail my selections of their respective types. 



The other names in the group do not need any special 

 examination. 



Dipus, with its type D. sagitta, is therefore the proper 

 name for the genus to which D. sowerbyi belongs. This 

 genus is readily distinguishable from Jaculus both by the 

 persistence of the small upper premolar, absent in Jaculus, 

 and by the much less development of the bullae, which do 

 not surpass the occiput posteriorly. The molars also are 

 slightly more complex. 



* Zimniermann quotes Schreber's plates £28 and 229, and if these were 

 really already published the name should date from them, but it would not 

 alter the conclusions here come to. Sherborn puts down their date of 

 publication as 1782, two years later than Zimmermann's book. 



