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Show 1882.] MR. FORBES ON THE PTERYLOSIS OF MESITES. 267 rounded, occupying nearly the whole of the fore part of the sole. First hind toe reaching just to the base of the second ; fifth to the end of the metacarpal of the fourth. Molars much as in the subgenus Isomys, broad and rounded, with numerous small but well-marked cusps. Approximate dimensions, in inches:- Forearm Incisors to Head and Hind and Ear- 1st upper Molar body. Tail. foot. hand. conch. Skull. molars. series. 6*2 5-8 1-01 1-18 0*65 - -38 -21 Judging from the analogy of other species, I should imagine that Mus nigricauda is an arboreal animal; for in nearly all climbing Rodents we find the rather short feet, large rounded foot-pads, and more or less bushy tail characteristic of the present species. The Dormice, Squirrels, and, most closely analogous of all, the Climbing Vesper-mice of Tropical America (Rhipidomys), may be cited as examples of forms which possess the above mentioned accompaniments of an arboreal habit of life. 4. Description of the Pterylosis of Mesites, with Remarks on the Position of that Genus. By W . A. F O R B E S, B.A., Prosector to the Society. [Received February 7, 1882.] When making some observations on the pterylographical and other peculiarities of Eupetes macrocereus', I expressed regret at not having been able to obtain any specimen of Mesites, which in external appearance somewhat approaches Eupetes macrocereus, to study its pterylosis also. Since then, having obtained through Herr G. Schneider, of Basel, a skin of Mesites variegatus, I have been able, from an examination of it, to complete our knowledge of this most peculiar form as regards the distribution of its feathers. All that was previously known of this part of the structure of Mesites was the existence in that bird of five pairs of powder-down patches2, M . A. Milne- Edwards in his paper on it3 having confined his observations to its osseous and internal structure 4. Those interested in the various opinions which have been held by naturalists as to the exact systematic position of Mesites, I will refer to M . Milne-Edwards's paper just quoted, only adding Mr. E. Bartlett's suggestion "that the 1 P. Z. S. 1881, p. 838. 2 Vide E. Bartlett, P. Z. S. 1877, p. 292. 3 Ann. Sci. Nat. (6) Zool. vii. 1878, art. 6. 4 An imperfect skull, extracted from the present skin, shows that the palate is schizognathous, the recurved maxillo-palatines being free in the middle line, and the vomer small and pointed-points not evident in Milne-Edwards's figure, his specimen, I believe, being somewhat imperfect, |