referred to the Genus Meriones. 267 
Molars decidedly larger than in JZ. crassus. 
Dimensions of the type (measured in the flesh) :— 
Head and body 125 mm. ; tail 125; hind foot 32; ear 17. 
Skull: median length 39; diagonal length 41°5 ; condylo- 
incisive length 35°5; zygomatic breadth 21°8; nasals 15 ; 
breadth of brain-case 18°3 ; bimeatal breadth 23; palatal 
foramina 7*7; upper molar series, crowns 5:9, alveoli 6:5. 
Bulle: horizontal diagonal length 17; length from back of 
bulla to front of premeatal swelling 15; suprameatal triangle, 
length 6°2, height 5°6. 
Hab. Tebuk, on the Hedjaz Railway, N.W. Arabia. Alt. 
2000’. 
Type. Young adult male. B.M.no. 10. 3.12.5. Original 
number 5. Collected 3rd January, 1909, by Douglas 
Carruthers. . 
This species agrees with MM. crassus in the very great size 
of the bulls, the measurement from the back of the bulla to 
the front of the premeatal swelling decidedly surpassing that 
found either in the Egyptian or Tripolitan large-bulla forms. 
In correlation therewith the suprameatal triangle is of a 
maximum size. From that species it differs by its larger 
molars and the greater posterior extension of its palatine 
. foramina. 
I have taken, as representing M/. crassus, a spirit-specimen 
from Mt. Hor, south of the Dead Sea, collected by Mr. H. C. 
Hart, of which the skull seems closely to agree with that 
figured by Sundevall. Another specimen in skin, from the 
type-locality Sinai, collected by Mr. Claude Wyatt, is notice- 
ably more ochraceous than MM. pelerinus, but, owing to the 
bullee of this example being lost, its determination is not 
absolutely certain. 
Meriones libycus caudatus, subsp. n. 
Group 6. Closely like true libycus of Lower Egypt, but 
with markedly longer and finer tail. 
General colour above warm buff, finely ticked with brown, 
below white with slaty bases to the hairs, as in true lebycus. 
Postauricular white patches fairly well marked. Tail 
decidedly longer than head and body, well-tufted, the tuft 
beginning halfway along the upper surface, and even below 
covering more than the terminal inch, the hairs attaining 
16-17 mm. in length. The tuft black, the rest buffy 
ochraceous. 
Skull apparently quite as in lébycus, the bulle very large, 
the suprameatal triangle small. 
