On a new Three-toed Jerboa from China. 279 
submarginal cell is very long and narrow, and the marginal 
cell appears to be open, as in all Pseudosiricide. 
Length of wing as preserved 45 mm., 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. 2596, with reverse. 
Related to Formicium, Westwood, from the Lower Purbeck 
at Durdlestone Bay. Handlirsch treats Formictum as a 
synonym of Pseudosirex, but it is clearly a distinct genus. 
XXXVII.—A new Three-toed Jerboa from China. 
By ARTHUR DE Care Sowersy, 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 three-toed 
jerboa belonging to the genus Dzpus, which were collected by 
Mr. A. L. Hall at Chih-feng in 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-feng ; 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 he was the original 
collector, I propose to name after Mr. Hall :— 
Inpus halli, sp. n. 
In size this new species is somewhat larger than D. sow- 
erbyi, which in turn was described as being larger than 
* Ann. & Mag. Nat. Hist. ser. 8, vol. ii. (Sept. 1908). 
