MAMMALIA. 



57 



everywhere, except at the extreme tips of the toes and at the heel. Mammae 8, 4 pectoral, 

 and 4 inguinal, as usual in the genus. 



The most remarkable character of this species is the presence at the end of the snout 

 of a semicircular lobe 1 which forms a flap completely covering the openings of the nostrils. 

 This lobe can, of course, only be well seen in the specimen preserved in spirit, in the dried 

 skins its presence can sometimes be detected, but not always. In the only spirit specimen, 

 an adult female, the flap measures about 0*3 inch in breadth, and is barely an eighth of an 

 inch long. It is hairy both outside and inside, the hairs being very short and rather scattered 

 inside ; the surface below the nostrils covered by the flap is also hairy. The use of this lobe 

 is evidently to keep out sand and dust from the air-passages. 



The following measurements are Dr. Stoliczka's, taken from the label of a specimen (sex 

 not marked) from Karghalik, and are doubtless from the fresh animal. On the label it is noted 

 that the specimen was the largest seen. I add in another column (2) the dimensions of the 

 specimen preserved in spirit, a female, and of course slightly contracted : — 





Inches. 



Inches. 



Length from nose to rump ...... 



. 5-5 



4-5 



Do. of tail without the hair at the end . 





5 



Do. of do. with do. 



. 6-25 



5-75 



Distance from eye to snout ...... 



. 0-8 





Do. do. to ear ...... 



. 0 3 





Length of ear from front base to tip .... 



. 0-75 



0-55 



Do. from orifice ...... 





0-5 



Greatest breadth of ear ...... 



. 0-6 



0-4 



Length of fore-foot ....... 



. (J-5 



(1-45 



Do. of hind-foot ...... 



. 1-4 



1-3 



following are the dimensions of a skull : — 







Metre. 



Inches. 



Length from occiput to end of nasal bones , 



. -037 



1-45 



Breadth across hinder part of zygomatic arches . 



. '019 



0-76 



Least breadth between orbits ..... 



. -007 



0-28 



Length of nasal bones ...... 



. -014 



0-55 



Do. of lower jaw from condyle to symphysis 



. -0195 



0-76 



In the skuil of this species, the lachrymal bone appears not to be anchylosed to the 

 adjoining bones, as it is in other forms of the genus. It is free in one fully adult specimen, 

 and entirely wanting, having evidently been lost, in two others, which have been extracted 

 from skins. I noticed that the process of the lachrymal, which in other species of Gerbillus 

 projects from the anterior angle of the orbit, was deficient in the first two skulls which I 

 examined, but it was only when I obtained a third skull, extracted from a specimen in spirit, 

 that I found this was due to the lachrymal not being united to the surrounding bones as it 

 usually is. 2 



This species is allied to G. meridianus 3 from the Caspian, but is considerably larger, 

 with a much longer tail. It is still nearer to G. tamaricinus* but differs in colour, in 



1 I am indebted to Mr. Oscar Fraser for calling my attention to this character, which he noticed when extracting the skull. I 

 had overlooked the lobe at my first examination. 



2 Although it is not very probable, I would suggest the possibility of the absence of this process in Ehombomys (Meriones 

 vpimusj, as noticed by Brandt (Bull. Acad. Sci. St. Pet., xiv, 1856, p. 76,) being due to the same cause. 



3 Mus meridianus, Pallas, Reise, ii, p. 702 ; JD'tpus meridianus, Pal., Zoog. Ros. As., i, p. 182.— Mas lotiyipes, Pallas, Glires, 

 p. 316. 



4 Mus tamaricinus, Pallas, Glires, p. 323. 



