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Show 1870.] DR. J. MURIE ON SAIGA TARTARICA. 459 arch, the orbital plates forming the outer boundary. The horns issue vertically above the small temporal fossae. The occipital region is relatively narrow and ovoid ; the semilunar condyles are no way prominent, and laterally bound a squarish foramen magnum. The compressed and, in this view, thin, paramastoid processes are but moderately long and perpendicularly set. The base of the skull (see fig. 6) is characterized-1st, by great orbital breadth ; 2nd, by the molar arch enclosing a rounded pterygo-malar space, posteriorly limited by a wide glenoid articulating surface; 3rd, the basioccipital region is broad relatively to its length ; 4th, the tympanic bullae of medium size ; 5th, the posterior nares very deep and moderately wide; 6th, dental portion of palate broad, but much narrower in front, slightly concave from behind forwards and across; 7th, the masseteric portions of the maxillaries bulge considerably beyond the alveoli; 8th, the premolar teeth incline inwards, a ridge running on to the premaxillaries ; 9th, the premaxillaries are produced forwards, in a flattened beak-like manner. I may further add, as a feature of some moment, that when the skull rests basally on a horizontal surface (the top of a table for example), the crown and nasals strike upwards, nearly parallel, at about an angle of 20° to the plane. This, so far as I am aware, is not the case with any other living Bovine form ; indeed, instead of the parietals and nasal tops exhibiting parallelism of plane, they trend downwards at a more or less obtuse angle from each other. Alces and Rupicapra offer no exception, though the horns of the latter are well nigh erect. (B) Individual Bones.-The parietals (Pa.) are short and low-arched. The coronal suture is strongly marked by two semilunar ridges, whose concavities are forwards ; and they blend together in a line with the sagittal suture, and run on in a slight ridge towards the prefrontal region. Between the horns, and partly to their rear, the frontal bone (Fr.) is moderately elevated, with shallow lateral depressions. In advance of their roots, however, the bone shelves rapidly to a lower horizontal level, continuous with the nasals. The osseous horn-core springs obliquely backwards, above and slightly behind the orbit. A large triangular supraorbital foramen is situate at their base, and half an inch beyond the outer raised border of the bone terminates in a small eminence joining the lachrymal. The broad fronto-orbital plate juts well outwards, producing the greatest cranial breadth at this part, as it forms the upper and posterior circuit of the orbit. An irregular bordered wedge-shaped portion of the frontal is inserted betwixt the nasal and lachrymal bones, which, however, falls short of, and is much higher than, the maxillary bone. The diminishment of the nasals and correlated extensive intermaxillary space, or open narial region, are the most extraordinary features of the skull. The stoutish ossa nasi (Na.), 1-inch long, together constitute an almost equal-sided triangle, instead of an elongate splint of bone surmounting the nasal arch, as in general |
