958 MR. w. B. DE WHTTON ON [Bec. 14, 



to have been recorded, not confined to this species, being common 

 to all true Xerus, but not found, I believe, in any Sciu7'm. In the 

 first place the middle of the palate is much arched and scooped 

 out or concave, leaving a prominent ridge of bone on either side 

 next the molar series. Secondly, the pterygoids are so peculiar 

 that it is hard to follow the homologies of the perfect bones of 

 the adult ; there is a prominent wing-like ridge, apparently a 

 continuation of the two ridges of the palate mentioned above ; 

 the inner face is concave and bowed inward, partially covering the 

 pterygoid fossa ; the apophyses at the back of the palate are very 

 much lengthened, so that the postnarial foramen is almost boned 

 over in the inter-pterygoid portion : the pterygoid processes, 

 besides being winged and flattened, are very much thickened 

 posteriorly, and are formed of very spongy porous bone : the 

 bone is hollow in the centre, there being a triangular cavity. 

 The whole structure is thus very unlike the form attained in 

 the adult state. This condition of the palate is observed until 

 the animal is almost full-grown, and the abnormal bone-covering 

 appears to be absorbed about the time the permanent premolars are 

 fully grown. 



As is usual in Squiri'els, the incisors are narrow and of a very 

 pale honey colour in the immature, increasing in size and depth 

 of colour with age till a fine orange-red is attained. 



Mr. Dodson noticed these Ground-Squirrels always among rocks ; 

 their food seemed to consist entirely of the fruit and kernel of 

 the Argand tree {Aryania sideroxi/lon), and they were never found 

 far away from these trees. It is believed that they sometimes 

 congregate into troops of 100 or so and migrate to fresh pastures. 



9. Geebilltjs shawi, Duv. 



(8), 1 c? , 7 $ . Morocco city (April), Mogador (June). 



10. Geebillus campesteis, Levaill. 



(7), 6 c? , 1 $ . Azimur, Dukalier, AUoo (April) ; Mogador, 

 Eas el Ain (June). 



11. Mrs BATTUS, L. 



(5) lias el Ain, Schaf el Kab, Ecru. Both the black and brown 

 forms represented. 



12. MUS MTTSCULUS, L. 



(2) Schaf el Kab (March). 



13. MtJs MtrscuLus gentilis, Brants. 



Mus gentilis, Brants, Muizen, 1827, p. 126. 



Head and body. Tail. Hind foot. Ear. 



mm. rum. mm. mm. 



c? . Enzel, 31st May 78 64 15 12 



d. Eas el Ain, Ahmar, 5th June. 77 55 14 13 



6 . Sierzet, Ahmar, 5th June . . 70 53 15 12 



" Caught in thorn-bushes." " Among stones in olive-grove." 



