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Show 1900.] STRUCTURE OF THE MUSK-OX. 717 case in Nemorhcedus and Haploceros; but in Ovibos it lies in front of the posterior margin of the symphysis. Rupicapra resembles Ovibos in this respect. The hamulus pterygoideus internus is larger, more pointed, and more curved backwards, in Budorcas than in Ovibos. The choanal open in both species behind the molars. This is a difference from Nemorhcedus and Rupicapra. The foramen infraorbitale is, in Budorcas as well as in Ovibos, situated rather far back, above the last premolar, but in Nemorhcedus above the first or second. Rupicapra and Haploceros resemble the latter. The processus postglenoideus is smaller in Budorcas than in Ovibos, but tbe shape of the surface for articulation is similar. These characteristics derived from the shape of tbe facial hones are of comparatively little value, as their possibility of variation is rather considerable. The construction of the fronto-parietal region of the skull is, I regret to say, only known to m e from the literature of tbe subject. According to the description of Budorcas published by A. Milne- Edwards 1, the frontal sinuses do not extend farther than just to the base of the horn-core, and are consequently less developed than in Ovibos. The elevation of the frontals, however, on which the horns of Budorcas are placed, " contient une multitude de grandes cellules en relation indirecte avec les fosses nasales" (op. cit. p. 370). Such an arrangement seems to agree very well with the corresponding one in the Sheep, but offers no resemblance to the massive exostoses on the head of the Musk-ox. The situation of the parietal in the Takin is also quite different from that of the Musk-ox. In the former this bone " se releve brusquement pour constituer la face posterieure de l'eminence ceratophore." This elevation of the parietal corresponds with the same in the Caprina, and, as in the latter group, this bone seems to be considerably shortened compared with the condition in the Antelopes. The fossa temporalis is in Budorcas, as in the Antelopes in general and in the Caprina, quite open posteriorly and upwards. The construction of the upper parts of the skull seems to indicate that the position of Budorcas in the system cannot be so very far from the Ovine branch. I have not had satisfactory material to express any decisive judgment, but I am inclined to think that Budorcas is most likely to be regarded as a primitive Sheep which has become specialized in a certain direction; but, on the other hand, its affinity to the Nemorhcedus group cannot be denied. The resemblance between Budorcas and Ovibos is only superficial Matschie, who lately has taken up this theory, seems2 to have based it on the following " gemeinsame Merkmahle ": (1) flat and broad metacarpal bones, (2) shape of i ' Rech. pour servir a l'Hist. Nat. d. Mammiferes,' Paris, 1868-74. 2 Sitz. d. Ges. Naturf. Fr. Berlin, Jahrg. 189S, p. 31. BBOC ZOOL. Soc-1900, No. XLVII. 47 |
