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Show 1871.] MR. ST. GEORGE MIVART ON HEMICENTETES. 61 teriorly (as in Centetes) in any hemispherical excavation between the basisphenoidal processes, which bend outwards to contribute to form the auditory bullae. There is no conspicuous foramen in the place of that one which in Centetes is situated in the roof of the hemispherical basisphenoidal excavation. Instead of that one foramen there are two minute ones towards the anterior end of the inferior surface of the basisphenoid. The pterygoid region is much more bullate than in Centetes. The foramen magnum is very large relatively, and looks almost directly backwards. On each side of it is a well-developed paroccipital process, anterior to which, but separated from it by an interspace, is a small process of the squamosal ; so that there are two processes on each side as in Centetes, only that the mastoid (placed between them) contributes to neither, instead of to both of those processes as in the last named genus. The small glenoid surface is bounded internally by a much smaller entoglenoid process than in Centetes. The tympanic bone is a mere ring. The prsemaxilla is very small, and does not nearly meet the anterior prolongation of the frontal as it does in Centetes. The nasals are distinctly separate for more than their anterior half, but they appear to anchylose together for their hindmost third. They extend backwards on the dorsum of the skull, about as far backwards as do the maxilla.. As in Centetes so in Hemicentetes, the parietals form more, and the frontals less of the roof of the cranium than in Erinaeeus. The zygoma is wanting, only a small process extending backwards and outwards behind as well as above the last molar. As before said, the mastoid appears on the outer surface of the skull, where it is subtriangular, with the apex upwards, and not bifurcating inferiorly, as in Centetes. The mandible has its ascending ramus only very slightly concave externally, its posterior margin between the condyle and the angle relatively much longer and more concave than in Centetes. On the other hand, the coronoid process is rather less raised relatively above the condyle. The inner surface of the ascending ramus above the dental foramen is much less concave. The horizontal ramus is not constricted behind the last molar. The condyle is rather elongated antero-posteriorly, and the distance from it to the coronoid process is not quite so great as from it to the mandibular angle. The last-mentioned part is flattened from above downwards, but so that it presents a slight horizontal projection, not only on the inside, but also on the outside of the vertical ramus. There is a small, rather pointed than obtuse, prominence on the inferior margin of the mandible, a little distance in front of the angle. This is sharper than in Centetes. There is a good-sized precondyloid foramen on each side, and in front of it a jugular foramen ; but I have not observed a definite carotid foramen. There is a venous foramen in the posterior part of the squamosal, near its upper border, and a minute opening behind the glenoid surface. The foramen ovale appears to be |