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Show 180 PROF. T. H. HUXLEY ON LEPIDOSIREN. [Feb. 1, under. The colour of the hair is rather lighter than in the Sambur the ears are not so large. The does breed freely every year with us. W e have liberated some in the bush, and given others away." Mr. Sclater exhibited the horn in question, and said that it appeared to belong to Cervus rusa, originally of Java, but which was known to have been introduced thence into the Mauritius many years ago (see Blyth, Ibis 1862, p. 92). Mr. Sclater thought it desirable that the facts of this transportation should be placed upon record, as this Deer might probably become a denizen of Australia, as had been already the case in Mauritius. The following papers were read :- 1. On the Position of the Anterior Nasal Apertures in Lepidosiren. By T. H . H U X L E Y , Sec. R.S. [Received January 7, 1876.] In the course of the discussion which followed my paper on Ceratodus, read before the Society on the 4 th of January, reference was made to the position of the anterior nasal apertures in Lepidosiren ; and they were affirmed to be within the mouth, inasmuch as they are situated between the upper and the lower lips. The anterior nasal apertures correspond with the primitive openings of the olfactory sacs, which, in all known Vertebrata, are invariably developed from the integument of the under aspect of the head, in front of the region which forms the roof of the oral cavity : and, in all the vertebrated animals in which I had specially studied the question, I had found the anterior nasal apertures to be situated in front of the upper lip and therefore outside the mouth. That they should be situated behind, or below, the upper lip, and therefore inside the mouth (so far as the cavity included between the lips may be properly called the mouth), appeared to me to be a singular anomaly, the existence of which, however, I was not prepared to dispute without reexamination of the facts. The point is, in various respects, of so much interest that I have lost no time in making the requisite investigation, with the result of leaving no doubt whatever in m y mind that in Lepidosiren, as in Ceratodus, the anterior nasal apertures are truly outside the mouth, not only in the sense of lying beyond the contour of the mandible, when this is shut against the palate, but in the sense of being situated on the underside of the head in front of the upper lip, and therefore altogether beyond the limits of any permissible definition of the oral cavity. When the mouth of a Lepidosiren (L. annectens) is laid open from below, and the palate and the contour of what has hitherto been termed the upper lip (Fig. p. 181, c a b d) are displayed, the latter is seen to present a median portion (a b) separated by a slight undulation from the two lateral prolongations c a and b d. The |