A Contribution to tlie Anatomy of Siren hicertlua. 063 



question. This is the Ramus palatinus posterior, and will be found 

 to be a branch of the alveolaris. The muscle may now be freed from 

 its origin upon epibranchiale, and gradually removed, working from 

 behind forwards. Underneath the posterior end lies the glossopharyngeal 

 nerve. 



This nerve issues from between the fibres of the levator arcus 

 primi, runs over the 1" epibranchiale, and finally bending forwards, 

 supplies the cerato - hyoideus internus and a portion of the externus. 



Anterior attachment. The anterior fibres arise from the 

 entire posterior border of the cerato-hyale. 



Posterior attachment. The entire external surface of 

 epibranchiale 1. 



Innervation. The posterior portion receives its nerve-supply 

 from branches of the glossopharyngeus, which runs beneath the muscle. 

 Ramus palatinus posterior supplies a few of its anterior fibres. 



8. Cerato-hyoideus internus (figs. 2, 4, ci). 



Preparation. After the removal of the preceding muscle, the 

 entire muscle is clearly visible, and one may see without further 

 preparation the origin , insertion and nerve supply from the glosso- 

 pharyngeus. In order, however, more clearly to observe its relations and 

 mode of attachement, the entire muscle may be removed by the for- 

 ceps, a few fibres at a time, beginning always near the middle and 

 tearing them off from their attachment. Enough will remain, after 

 the bulk of the muscle has been removed, to indicate its former po- 

 sition. 



Anterior attachment. This is at the angle formed by the 

 cerato-hyal and the 1'' basibranchial, the muscle being attached 1) to 

 the external surface of basibranchiale 1, 2) by a long band-like tendon 

 to the hypohyal, 3) to the membrane forming the capsule of the 

 point between cerato-hyale and basibranchiale 1, 4) to the posterior 

 surface of the anterior interior end of the cerato-hyale. 



Posterior attachment: 1) upon the anterior border of 

 ceratobranchiale 1, with the exception of its anterior end, 2) upon the 

 ventral third of the anterior border of epibranchiale 1, and upon the 

 point between the two portions ; 3) a few fibres arise from the ventral 

 surface of the oval mucous membrane in the interspace between cera- 

 to-hyale and the 1*^ gill arch. 



Innervation. The glossopharyngeal nerve. 



