7i!6 



SCIENTIFIC RESULTS FROM THE MAMMAL SURVEY. 



No. XX. 



By Oldfield Thomas, f.r.s. 



(Published by permission of the Trustees of the British Museum). 



^.— NOTES ON THE GENUS CHELI0NE8. 



When writing on the members of the large genus Meriones 

 (A. M. N. H. (9) III. p. 263, 1919), I came to the concision 

 that the Indian species of recent years known as Meriones hurriance, 

 the Desert Gerbil, is so distinct from all of them that it deserved 

 generic separation, and I founded for it the genus Cheliones. 



Its chief chai'acters are that the animal is of a more burrowing 

 habit than ordirar}^ Meriones, and in correlation with this, the 

 ears are quite short, the fore-claws elongated, and the skull 

 strongly built, much bowed, and with comparatively small bulla3. 

 In Meriones the fore-claws are decidedly shorter than the hind, 

 the ears are long, the skull lightly built, and the bullse very large 

 — all characters of surface-living, desert animals. 



The range of the genus extends from the North-West frontier 

 and Baluchistan, just penetrating Afghanistan, on the west, 

 through the great Indian Desert of Rajputana to Delhi, on the 

 east, and Kathiawar on the south. 



Throughout the greater, and lowland, part of this area the 

 species, though variable, shows no local specialization, but when 

 the higher grounds of the North-West Frontier and Baluchistan 

 are reached we get a certain difference which may be suitably 

 recognized by the formation of a special sub-species. 



Cheliones hurriance collinus, subsp. n. 



Size apparently slightly greater than in true hurriance, but 

 owing to the scarcity of specimens in which the basilar suture has 

 closed, it is difficult to make certain of the degree of difference. 

 Colour above on the average darker and grayer, while below the 

 whole under surface, apart from the white chin, is broadly and 

 prominently washed with strong buffy, the bases of the hairs being 

 dark slaty, the total ventral colour resulting being conspicuouslj^ 

 darker than in hurriance, in which the hairs are usually 

 washed with white or pale buffy, and their bases are either wholly 

 white or at most pale slaty. 



Skull slightly larger and the palatal foramina longer and more 

 widely open than is usual in hurriance, though there is much varia- 

 tion in this respect. 



Dimensions of the type: — Head and body, 150 mm. ; tail, 150 ; 

 hindfoot, 32-5; ear, 11. Skull, median length, 36-7; diagonal 



