180 PROF. T. H. HUXLEY ON LEPIDOSIREN. [Feb. I, 



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. 

 We have liberated some in the bush, and given others awav." 



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. Huxley, Sec. R.S. 



[Received January 7, 1876.] 



In the course of the discussion which followed my paper on Cera- 

 todus, 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 open- 

 ings of the olfactory sacs, which, in all known Vertebrata, are in- 

 variably 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 my 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 alto- 

 gether 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 



