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Show 204 DR. R. W. SHUFELDT ON [Apr. 1, pigmented ; while it fits very closely to the superimposed bones the skull, thus giving rise to several paired pits of greater or less depth, and an azygos one that stands between the apertures of the posterior nares. These latter are of fair size, somewhat rounded in outline, and separated from each other by a transverse distance of nearly a centimetre in the adult. From either one there leads forwards a doubly curved slit-like groove, the lips of which are flexible and in contact by their edges for their anterior two-thirds. This groove terminates in front in a small, rounded opening, which is the mouth-entrance to the cavity containing the Organ of Jacobson. A line drawn perpendicular to the plane of one of the posterior narial openings would be found to be considerably in front of the eye of the same side, and still further in front of the brain. In the dried skull the direction of the narial chamber lies longitudinally; but in the living animal the external nostril is laterally situated, so that an angle is formed in the passage in front. The Tongue.-Bocourt and Boulenger have given a superior view of the tongue in H. horridum, and it has been figured by other anatomists. It is thick and broad at its base, rather thin and acutely but not deeply bifid anteriorly. It is more than twice as wide behind than it is in front, having rounded margins for its thicker parts. Peculiar papilla forming epithelium is seen covering the hinder two-thirds of its free surface, which is gradually developed from the smoother coat of the fore part of the organ. A faint medio-longi-tudinal groove marks its superior aspect, aud it is bound down by a thick median fraenum ventrally. Dissection shows it to be composed of two symmetrical halves, which are separated from each other by a thin fibrous septum, found in the medio-vertical plane. Posteriorly, extending deep into its base, we find the rod-like body of the hyoid, and about it considerable adipose tissue is deposited. Either lateral half of the tongue possesses two special muscles that here require description :- 120. The Lingualis.-This is purely an intrinsic muscle of the tongue, which arises in the substance of its base, and, extending longitudinally through the entire dorsum, its fibres are gradually lost as it comes to tbe apex. It overlies the genioglossus aud the genio-hyoideus. 121. The Genioglossus.-A muscle which must be considered but partly intrinsic to the tongue I propose to describe under this name. It is seen to arise, upon either side, from the inner aspect of the mandible near the symphysis, and its fibres passing backwards and upwards, spreading out as they do so, the muscle at once becomes entirely incorporated in, and devoted to, the tongue. Its insertion for the most part is limited to the hinder half of the organ, extending from the fraenum to the base, and outwards as far as the lateral margin. The broad, thick, fleshy, unensheathed and independent tongue of Heloderma, then, is a very different affair as compared with the |