OF REPTILES AND BIRDS. 11 



The nervus glossopharyngeus is, in most reptiles, a distinct nerve ; but in some it does 

 not have this independence, and is then always united with the vagus." p. 137. 

 Desmouslins (ii. Pt. 463, 6) states that it is wanting in Ophidia ; Bendz, as we have 

 seen, found it united with the vagus in Tropidonotus, while Vogt (xvi, 44, 49) says it is 

 distinct in Crotalus horridus and Coluber siculus. 



" The trunk" (of the hypoglossus) " usually forms two branches, of which the anterior 

 supplies the muscles of the tongue, the posterior the M. sternohyoideus and omo-hyoideiis. 

 In snakes, I found that the lingual branches enter into anastomosis with a branch from 

 the iV. aheolaris inferior, N. trigemini. Desmouslins (ri, ii, 455), has made a similar 

 observation upon Crotalus, where he describes a communication with the N. llngualis, 

 N. vagi; but since he denies (the presence of) the hypoglossus in Ophicta, I 

 shall therefore make no close comparison with what I have found in Tropidonotus and 

 Lacerta." p. 148. 



The observations of previous observers contain, as far as I am awai'e, no mention of the 

 three nerves, fig. 7, A, B, C, which enter the tongue, but only of the third, C, the hypo- 

 glossal. Bendz makes no reference to a lingual branch of the glossopharyngeal. As 

 regai'ds the trigeminal lingual nerve, it has been said to be wanting, a statement which is 

 repeated by Stannius in his Lehrhxijcli. Bendz {vide supra) states that the hypoglossal 

 receives a communicating branch from the N. alveolaris inferioris, by which the tongue is 

 indirectly supplied with trigeminal fibres. 



The hypoglossus, fig. 1, C, runs backward beside the tongue, fig. 10, C, before pen- 

 etrating the muscle, which it does immediately behind the point where all the transverse 

 lingual muscles stop. As it enters, it separates into the two branches already described 

 by Bendz {vide sujjra); 1, a smaller one running backwards along the outside of the 

 ceratoglossus, fig. 11, c"; 2, a larger one which penetrates into the substance of the 

 cerafoglossus, and then runs forward in the midst of that muscle, giving off" branches as 

 it goes. The main trunk is surrounded by a vascular fibrous connective tissue, which is 

 very distinct from the muscular fibres around it, fig. 10. This same figure also shows 

 the hypoglossus upon the outside of the ' tongue, occupying the same relative position 

 which is held further forward by the nerve B, and still further forward by the nerve A. 

 The amount of connective tissue around the hypoglossal nerve in the tongue gradually 

 diminishes, becoming hardly more than a sheath of the nerve in the free part of the 

 tongue. At the level of the fork the nerve is reduced to a few hardly distinguishable 

 branchlets. 



I am unable to say what is the origin and distribution of the other two nerves. Fig. 1, 

 B and A. From analogy with mammalia, they are the lingual branches respectively of 

 the glossop)haryngeus and trigeminus. 



The anterior nerve, fig. 1, A, enters the sheath, penetrates underneath the M. genio- 

 vagineus, and runs backwards, immediately underlying the sub-mucosa of the sheath, to 

 the point where the sheath and the tongue unite. Further than this I have not followed 

 its course with certainty, but I think it probably bends forward, and runs along the side of 

 the tongue, outside of the muscular core, where there is a nerve, fig. 9, A, which how- 

 ever, appears only in sections through the base of the free part of the tongue, and not 

 further forward, and therefore is apparently distributed to the side of the base. If these 



