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Show 958 MR. W. E. DE WINTON O N [Dec. 14, to have been recorded, not confined to this species, being common to all true Xerus, but not found, I believe, in any Sciurus. 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 Squirrels, 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 (Arganla sideroxglon), 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. GERBILLUS SHAWI, DUV. (8), 1 o*, 7 2 • Morocco city (April), Mogador (June). 10. GERBILLUS CAMPESTRIS, Levaill. (7), 6 <S, 1 2 • Azimur, Dukalier, Alloo (April); Mogador, Bas el Ain (June). 11. Mus RATTUS, L. (5) Bas el Ain, Schaf el Kab, Ecru. Both the black and brown forms represented. 12. Mus MUSCULUS, L. (2) Schaf el Kab (March). 13. Mus MUSCULUS GENTILIS, Brants. Mus gentilis, Brants, Muizen, 1827, p. 126. Head and body. Tail. Hind foot. Ear. mm. mm. mm. mm. 3 . Enzel, 31st May 78 64 15 12 6 . Eas el Ain, Ahmar, 5th June. 77 55 14 13 o*. Sierzet, Ahmar, 5th June .. 70 53 15 12 " Caught in thorn-bushes." " Among stones in olive-grove." |