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Show 1870.] DR. J. MURIE ON SAIGA TARTARICA. 465 and only narrows towards the rostral insertion of the vomer, where it is convexly ridged. The long lamellar external and internal pterygoid plates are so closely conjoined as to be with difficulty recognized as separate elements. The former, lanceolate, and \ inch in greatest breadth, springing in front of the sphenoidal foramen, does not, as in Capra and Ovis, trend so horizontally forwards, but strikes more obliquely down, and suturally connects itself with the vertical palatine plate. Its posterior edge agrees with the Antelope's in being narrow, and not everted, as in Sheep and Goats. The latter, internal spheno-pterygoid plate is even more delicate at its root, and arises close to the posterior edge of the pterygo-palatine plate, thence running backwards at a sharp angle to the external pterygoid plate, lays like a splint inside it, and again curves forwards, to be prolonged into a thicker but nevertheless slender rod, terminating in a short hamular process. The alisphenoids, as in Ovis, present only a rudiment of that bony plate so conspicuously developed forwards at the back of the orbit in Pantholops and other of the Antelopes. The sphenoidal wing in Saiga is altogether small, obliquely ridged, contracted antero-posteriorly, and curved sharply backwards between the postfrontal and squamo-temporal elements. The orbito-sphenoid seen from below has a larger superficies than the alisphenoid, though in itself small. It has a smooth concave surface, the foramen opticum obliquely penetrating it just above the root of the internal spheno-pterygoid plate. (C) The Mandible.-The dentary portion of the body of the bone, when the mandible is placed in natural position, has a moderate curvilinear direction upwards and forwards. At the last molar its vertical depth is 1\ inch, but, correspondingly, less than 1 inch at the premolar. Anteriorly the diasteme narrows very considerably in a tapering manner, and then widens into a somewhat scooped or shovel-shaped symphysial part, 1 inch long and as much wide, into which the horizontally placed incisors are inserted. A diminutive ridge runs backwards from each outer incisor towards the molar alveolus. The mental foramen is situated, outside, immediately behind the symphysis. The ascending ramus, as mentioned, strikes upwards at nearly right angles to the dental plane, the angle being produced as a thin but broad and rounded sweep of bone. The head of the condyle is short-necked, the articular surface transversely oblong and very gently concave. The sigmoid notch is shallow and narrow, the long coronoid process of nearly uniform breadth throughout. The inferior maxilla in the male measured 7 2 inches horizontally from symphysial extremity to ramal angle; and adding an inch for the median incisors, the extreme length would be 8 inches. (D) Dentition.-In the Society's adult male specimen the set of teeth were deficient in the anterior lower premolar and two middle incisors. I found the skeleton at the College of Surgeons more complete, and answering to Pallas's brief statement of the dental numbers in the full-grown animal. The formula, therefore, of the permanent dentition is that of other hollow-horned Ruminants, to wit:- LIS C.g, P.M.g, M. fEf = 32. |