On a new Three-toed Jerboa from China. 279 



submargiiiul cell is very long and narrow, and the marginal 

 cell appears to be open, as in all Pseudosiricidae. 



Length of wing as preserved 45 rain., probable total length 

 at least 50 mm. 



Basal nervure falling just short of transverso-medial ; 

 lower section of basal nervure arched, 5 mm. long, forming 

 nearly a right angle with the upper section, as in Formicium, 

 the upper section 2 mm. long ; first discoidal cell 5 mm. long ; 

 second 5*5 mm. on upper side and 8 on lower; second sub- 

 marginal cell about 6 mm. long and hardly 2 mm. wide; 

 marginal cell about 2*4 mm. wide (deep), the marginal 

 nervure (radial sector) perfectly straight. The cubital nervure 

 diverges from the marginal, so that 10 mm. beyond end of 

 second submarginal cell they are 4'3 mm. apart. 



Bagshot Beds, Bournemouth [J. S. Gardner^. British 

 Museum, I. 259G, with reverse. 



Related io Formicium,^ Qsiwoodi, from the Lower Purbeck 

 at Durdlestone Bay. Handlirsch treats Formicium as a 

 synonym of Pseudosirex^ but it is clearly a distinct genus. 



XXX YIL — A neio Three-toed Jerboa frotn China. 

 By Arthur de Carle Sowerby, F.Z.S., F.R.G.S. 



In a collection of mammals presented by Mr. J. D. de La Touche 

 to the British Museum are two specimens of a tliree-toed 

 jerboa belonging to the genus Dipua, which were collected by 

 Mr. A. L. Hall at Chili-feng \\\ North-eastern Chihli on or 

 near the Mongolian border. They represent a form closely 

 related to Dipus sowerbyi, originally described by Mr. Oldfield 

 Thomas* from specimens collected by myself in the Yu-lin-fu 

 district on the border of the Ordos Desert, some 500 miles to 

 the south-west of Chih-feug ; but since they present diffe- 

 rences in cranial and body measurements, as well as a slight 

 variation in colour, and having regard to their geographical 

 distribution, they may be considered as belonging to a distinct 

 species, which, in view of the fact that lie was the original 

 collector, I propose to name after ]\Ir. Hall : — 



Dipus hallif sp. n. 



In size this new species is somewhat larger than D. sow- 

 erbyi, which in turn was described as being larger than 



• Auii. & Mag. Nat. Hist. ser. 8, vol. ii. (Sept. 1908). 



