21(5 THE VOYAGE OF H.M.S. CHALLENGER. 



immediately beneath the inner border of the stylo-hyoid. It arises from the inner surface of the 

 symphysis, and from the inferior margin of the lower jaw opposite the 2nd, 3rd, and 4th incisors. 

 It takes a small turn to the middle line and meets its fellow, and is inserted into the inferior 

 surface of the body of the hyoid bone. It is supplied by the hypoglossal nerve. 



The Muscles of the Tongue. 



The extrinsic muscles are the stylo-glossus, hyo-glossus, genio-hyo-glossus, and palato-glossus 

 (see Soft Palate). 



The Stylo-glossus both in Phoca vitidina and Arctocephalus is a small muscular band which arises 

 from the ventral surfaces of the stylo-hyal and epi-hyal, and goes obliquely forwards over the end 

 of the hyo-glossus, ending at the tip of the tongue. It is supplied by the hypoglossal nerve. 



The Hyo-glossus both in Phoca vitulina and Arctocephalus is a quadrilateral band, and arises from 

 the thyro-hyal, slightly from the basi-hyal and cerato-hyal. It extends along the under surface of 

 the tongue to its tip beneath the stylo-glossus. It is supplied by the hypoglossal nerve. 



The Genio-hyo-glossus both in Phoca vitulina and Arctocephalus is thin and triangular. It arises 

 by muscular fibres from the inferior margin of the lower jaw, reaching from the symphysis to opposite 

 the second last molar tooth, and is blended near the symphysis with its fellow. The posterior fibres 

 go to the body of the hyoid bone and some to the pharynx ; the middle to the middle of the 

 tongue ; the anterior to the front of the tongue. It is supplied by the hypoglossal nerve. 



The Muscles of the Pharynx. 



These are as usual, the inferior, middle, and superior constrictors, and the stylo-pharyngeus 

 (for the palato-pharyngeus and salpingo-pharyngeus, see the Soft Palate). 



The Inferior constrictor in Phoca vitulina arises from the side of the cricoid cartilage, &c, as in 

 human anatomy, and almost hides the middle constrictor. It is supplied by the pharyngeal plexus, 

 and the external and recurrent laryngeal nerves. 



The Middle constrictor in Phoca vitulina arises from the posterior cornu of the hyoid bone, 

 along its anterior surface, and slightly from the cerato-hyal, and is inserted as usual. It is supplied 

 by the pharyngeal plexus. 



The Superior constrictor in Phoca vitulina arises from the inner surface of the stylo-hyal and 

 epi-hyal, and from the fibrous tube of the pharynx between the two tympanic bulla?. It is inserted 

 into the median raphe of the pharynx and to the vertebral column between the two recti antici 

 majores. It is supplied by the pharyngeal plexus. 



The Muscles of the Soft Palate. 



These are the levator palati, tensor palati, palato-glossus, palato-pharyngeus, azygos uvulae, and 

 salpingo-pharyngeus. 



The Levator palati both in Phoca vitulina and in Arctocephalus arises from the tympanic bulla below 

 and a little to the inner side of the Eustachian tube, and from the inferior surface of that tube. It 



