| OCR Text |
Show 704 DR. E. LONNBERG ON THE [June 19, but it is hardly as large as in the calf, measuring 42 mm. in length but only 17 in width. In an adult bull the same measurements are (not counting spines) 31 m m . in length and 14 in width. The shape of the bulla cannot therefore be of classificatory value in this animal. The pars mastoidea is visible on the occipital surface as a narrow strip between the paroccipital and the squamosal, which latter forms the lateral margin of this surface. At the upper end of the mastoid there is, in the calf, a small separate bone visible, with an outer surface measuring 8 m m . in diameter. It is intercalated between supraoccipital, paroccipital, mastoid, and squamosal.^ It has already been mentioned that the squamosal constitutes the lateral margin of the occipital surface. This bone forms a strongly projecting edge posteriorly, which extends downward and forward in an even curve to the base of the zygomatic process, thus making a posterior termination and a broad floor to the temporal groove, which is roofed over by the horns. There is accordingly only an (in the bull, narrow) opening posteriorly in an oblique upward direction over the parietal zone. Biitimeyer 1 seems to lay some weight on this opening as a difference from the Oxen and a resemblance to the Sheep. But, compared with the condition found in the Italian Buffalo, there is not much difference in this respect, and in nearly all Antelopes " die Schlafengrube offnet sich . . . auch nach oben." It is consequently only the most specialized members of Bos in which " die Parietalzone seitlich die Schlafe iiberdacht," as the same author in his first paper rightly puts it. Later Biitimeyer, like some other authors 2, seems only to think of two possibilities, i. e. " Is Ovibos a Sheep or an O x "? and then every aberration in structure from tbe specialized type is regarded as a similarity to the ovine one, even if it is a feature common to most ruminants. The articulating surface for the condyles of the mandible is very broad (see fig. 8, p. 709) and, to judge from m y material, more convex in the cow than in the bull, in which it is almost flat. There is a broad and strong jyi'ocessus postglenoideus. So far as m y material allows a judgment, there are always two foramina temporalia in the Musk-ox, but only one in Sheep or Goats. This is, however, a less important and variable characteristic 3. The great development of the orbital tube is one of the most conspicuous features of the Musk-ox skull, as has also been mentioned by previous authors. [It is formed by the frontal to, roughly speaking, an extent of a little more than two-fifths (more exactly j5 T) of the posterior and upper portion, by the lachrymal to one- 1 ' Die Rinder der Tertiar-Epoche.' 2 Boyd Dawkins, for instance. 3 Nemorhesdus. Cephalophus, Bos taurus, &c. seem to have two ; Antilope, Saiga, Gazella, Rupicapra, Bos bubalis, &c. only one. This is mentioned here only because Riitimeyer says (Rind. Tert. p. 104): "Tm iibrigen folgt der Schadelbau (viz. of Ovibos) ..... demjenigen von Schafen bis in kleine Details, wie etwa Gestalt von Gefass und Nervenrinnen." |
